What is your single favorite development tool?
Visual Studio 2008 :)
My brain. I don't think I'd be able to code without it.
My editor, vim.
Being able to make changes to your code and revert them, or to be able to merge your changes painlessly with your co-workers, is worth its weight in gold. Also, you're backing up your code, which is nice when your computer goes all smokey.
Firebug . Doing web development without it is like typing with one hand instead of two. http://getfirebug.com/
Notepad++  http://notepad-plus.sourceforge.net/uk/site.htm
Google  http://www.google.com
ReSharper for Visual Studio
The coffee machine.
For Java/ J2EE  definitely Eclipse :)
Unix utilities. I even install Cygwin  when in Windows. http://en.wikipedia.org/wiki/Cygwin
The pencil and paper sitting next to my keyboard.
Emacs is the best.
A door that can be closed.
A pair of headphones is a good productivity tool.
Launchy . Can not use a PC at all without it. http://www.launchy.net/
"Place a rubber duck on your monitor and describe your problems to it. There’s something magical about stating your problems aloud that makes the solution more clear." -- from the Pragmatic Programmer
Seriously! Development software which makes me keep reaching for the mouse is a productivity haemorrhage.
GCC - GNU Compiler Collection
Git  http://git-scm.com/
Valgrind  http://valgrind.org/
VS2008 + MSDN + Google.
Multi-monitors... or a really high-res monitor.
It's so hard to develop with limited screen space.
So many features, exactly where I expect them to be -- and I'm always discovering more new and useful features. http://www.eclipse.org
Vim  and the Python interpreter. http://en.wikipedia.org/wiki/Vim%5F%28text%5Feditor%29
One word: caffeine.
I'm going to have to say Subversion again, although I really mean just about any revision control system. It's great to be able to try experiments and know that you can always go back to what worked before, or to reclaim a bit of code that was accidentally deleted three days ago.
Rammstein  - German rockband. http://en.wikipedia.org/wiki/Rammstein
IntelliJ  http://www.jetbrains.com/
Delphi  http://en.wikipedia.org/wiki/CodeGear_Delphi
Visual Studio wins hands down.
Experience and knowledge. Seriously, tools can be immensely valuable to a skilled programmer. But despite all the marketing claims, the tool that can make up for a basic lack of skills hasn't been invented yet.
Subversion. Even if you're a solo programmer, version control is a vital tool. And WinZip is not a version control system. :-)
ReSharper is my #1 choice as well. This tool has so many time savers that I just can't code without it.
I would say #2 would be Reflector. This has given me a greater understanding of third party type systems including those in the .Net Framework.
Time spent thinking.
Eclipse and sometimes vi/ Vim . http://en.wikipedia.org/wiki/Vim%5F%28text%5Feditor%29
Visual Assist X  ... why hasn't anyone mentioned this yet? It's a wonderful "can't do without" tool. http://www.wholetomato.com/
Firebug  - the all-in-one JS debugger (and profiler), CSS analyzer (and inspector), DOM inspector (and manipulator), and more for Firefox.
You can guess that my job involves front end work for websites, can't you? http://getfirebug.com
A boss who:
In my current job I have my own office, with a door that closes, a fast laptop, two monitors, and a reasonably comfortable chair. But I don't have a boss that fits the description above.
I wouldn't have guessed what a productivity hit it is until working under these conditions.
It only took a few snide repetitions of "As I already told you..." before I decided that, since apparently I don't have photographic recollection of what I've already asked him and what I haven't, and since apparently it's a really big deal to ask something twice, I should quit asking questions at all.
Vim, regexps, sed, awk, bash.
For me, it would be Emacs.
Even when I'm using VisualStudio for compiling, Emacs is my editor, and I spend nearly all day in there.
Headphones and gangster rap.
I don't even listen to rap when I'm not programming...maybe it's the "violence" in the lyrics or the bass keeping me on track, but it seems to heighten the senses and I swear I make less mistakes when I'm listening to old-school Tupac or Eazy-E.
I know it's not normal, but try it.
Another pair of eyes...
Getting someone else to look at your code - whether it is to break a blocking issue you have with what you are developing or doing a code-review before a critical check-in, other peoples' input into your thought process can be invaluable.
NUnit . http://www.nunit.org/index.php
Your question registered in my brain as "What's your favorite editor?" I have to answer Emacs.
Visual Studio 2008, MSDN Library. Can't do anything without it.
Visual Studio 2008
Balsamiq Mockups .
You can knock out screen layouts so quickly that you can get an idea of how a month's worth of coding will look an afternoon and find mistakes before you spend hours developing them. http://www.balsamiq.com/products/mockups
The Great Almighty Internet
I'm a web app developer, and my favourite tools are:
But my top favourite dev tool has to be Firefox  with a few addons:
I wouldn't be "lost" without it, but I would surely be very grumpy in its absence.
Git adds all the features I need and can interact easily with svn (git-svn).
Eclipse! (Java, Pydev, PDT!, UML, etc.. etc..)
My tops are Google (including MSDN and the MSDN's of each language like php.net) and a great IDE (like Visual Studio).
eclipse (or: my IDE). I'd get totally nuts programming Java without an IDE.
NUnit all the way.
For Oracle stuff, TOAD  takes some beating IMHO. http://en.wikipedia.org/wiki/TOAD%5F%28software%29
Textmate  for coding, git for its wonderful branching and (especially) easy merging, and Google for when I need to track down example code. http://en.wikipedia.org/wiki/TextMate
My favorite pen.
Communication is necessary.
I also like JEdit.
Visual Studio 2008! For all the bitching (some) people do about Microsoft, I don't think they can honestly argue that the company hasn't produced some great (and affordable) development tools.
It's an incredibly powerful add-in for VS that speeds development. http://www.devexpress.com/Products/Visual_Studio_Add-in/Coding_Assistance/index.xml
Actually, it can't be one.
For Java development:
But if I have to choose only 1, then Eclipse :)
The CodeRush/Refactor Pro  addins are, I think much more robust than the Resharper et all offerings.
Visualization Tools - Quickly see the essence of the code you're working on because Clarity is good - Noise is bad.
Advanced Selection Tools - Select and radically manipulate code with efficiency, because working with selections the old-fashioned way is an exercise in tedium.
Clipboard Tools - The clipboard as your trusty sidekick because a smart clipboard is a whole lot better than a simple one.
Navigation Tools - Move through source code faster because fishing for code is a distraction that you don't have time for.
Code Templates - Create common code blocks fast because manually typing in all those characters of a try/catch block or a for-loop takes way too long. Cutting down on the repetition in your day can help reduce the risks of long term damage.
CodeRush Extensibility - The extensibility of CodeRush is it's single greatest feature because through custom extensions you can help newbies adhere to team standards, implement that great VS feature idea you had, or simply exploit all the killer plug-ins submitted by the CodeRush community.
Coffee. And I'm dead serious when I say this - a walk down to the breakroom for a cup of coffee provides me enough time to get away from my desk and muse over any problems I might be running into.
A whiteboard and a few markers are the best tool when coding. It is invaluable for figuring out flow and structure and relaying those ideas to co-workers.
Firefox with these addons:
For .NET development LINQPad  is indispensable.
Test your .NET code before answering a Stack Overflow question. (That is just one use.) http://www.linqpad.net/
Visual Studio 2010
Wireshark  http://www.wireshark.org/
My keyboard ;-)
... actually, my favorite is the IntelliJ IDEA . http://en.wikipedia.org/wiki/IntelliJ%5FIDEA
My state of the art quad core computer with dual monitors.
ProGuard  Java code obfuscator/shrinker.
Shameless self plug: I also find my own RefactorBuddy  invaluable. http://proguard.sourceforge.net
My coffee machine. Without it, my mind doesn't work.
In all seriousness, my single favorite development tool is my mind. I can develop software using a plain text editor and a compiler. It might suck, but I can. But I can't develop software without the ability to think, and think clearly.
A Herman Miller Embody  chair. http://embody.hermanmiller.com/
Despite the advances in high level languages, we still manually string code together line by line. Resharper definitely helps automate that process.
Reflector is more of a knowledge tool, and I only crack it open when I want insights to debugging.
I often encourage colleagues to think in Notepad++, and spell out there thoughts without having to be bound to namespaces, references, etc.
In no particular order, Emacs, Git, grep, and Firebug when I'm doing web dev.
WinDbg. Debugging, tracking down memory leaks (wherever they may lie), crash dumps... this is the development that I do most and that is the tool that I use most.
WebDeveloper toolbar add-on for Firefox.
XCode of course
TotalCommander  + TC PowerPack (tons of useful plugins) http://www.ghisler.com/
GNU Coreutils . I think this is what people who said "bash" actually mean.
And no, BSD userland is not a substitute. http://www.gnu.org/software/coreutils/
Coffee, all ten of my fingers, and for the severe jam-ups, google & the internet, cause chances are someone else out there ran into the same wall you did
Notepad++; it's just an editor, but I use it so much that I think losing it would have the biggest impact.
Chris Pederick's Web Developer  toolbar plugin for Firefox. http://chrispederick.com/work/web-developer/
Emacs, for me.
Ant  for a single command build process. http://ant.apache.org/
Visual Studio 2008 TeamSystem with Resharper, GhostDoc and Reflector. This is actually all I need :)
cscope  http://cscope.sourceforge.net/
Kate , which I now use on both Linux and Windows and used on my Mac, when I still had one. http://en.wikipedia.org/wiki/Kate%5F%28text%5Feditor%29
Reflector is wonderful.
Kate  on KDE and on all other systems JEdit, they are both text editors. Kate is really good for Linux development because it has a console built in, and JEdit has the best search and replace tool I have found. http://en.wikipedia.org/wiki/Kate%5F%28text%5Feditor%29
Visual Studio 2008
Eclipse for Java, and Emacs for everything else
VS2008 SP1 & SSMS
Apparently many people can't read the title :(
my brain ...
can't belive you all missed #1 ;)
Comparison tools like BeyondCompare and SQL Examiner
Diet Mountain Dew.
ANT  http://ant.apache.org/
visual studio, beyond compare, tortoisesvn, visual assist
Visual Studio, TortoiseSVN, PSPad
A debugger with the ability(when a break is sent) to view the values of variables/pointers and that can print out the call stack.
If I can view the value of a function and how the program got into the scope it did, I can debug pretty much anything with some time and patience.
Visual Assist anyone?
I would have picked source control first but that's already been mentioned.
A white board - I am such a visual thinker that I have to draw everything. I prefer a white board because I can share with many people, quickly erase and redraw, and even leave it on my wall for a while as a reminder.
Does pen and a pile of paper count as a single tool?
This lets you easily run (and debug) single NUnit tests from the IDE. http://www.testdriven.net/
TestDriven.NET, ReSharper. You know, the usual suspects.
One tool, though, that I really like is VisualSVN. Being able to use Subversion from the IDE and letting it handle all the redundant tasks (such as adding, renaming, etc..) is really valuable. Zero friction. Is it most valuable? Not sure.
I don't think the value is always just in the tool. Rather I think the value is using the tools to their fullest capabilities.
You have found value in Resharper, other may not see that same value, until they understand what it is capable of.
I personally have found value in the DevExpress Addins (already mentioned), as well as the DPack Addin . Those two help enhance my effectiveness in VS.
I have taken the time, and continue to take time to learn new/interesting ways of using them. http://www.usysware.com/dpack/
With freely available, or custom-written plugins it get's all the features of the big IDEs with none of the slowness and bloat.
And it is cross-platform and can be used to develop with any language.
Refactoring: Bicycle Repair Man (bike.vim), Rope (rope.vim)
Autocompletion: Omnicomplete, Supertab.vim
Anything Else: Python bindings
Visual Studio 2008
I just couldn't survive very long without good ol' vim.
Geany  I think. I use it to write my code, to think my code and I use is interface to compile my code. So what can I want more? http://www.geany.org/
IntelliJ IDEA 
I also use eclipse, but the more i use eclipse, the more I appreciate the elegance of IntelliJ. http://www.jetbrains.com/idea/
VirtuaWin  is very important for managers who when things get dumped onto your lap mid-way while you are currently working on something else. http://virtuawin.sourceforge.net/
WinMerge  http://www.winmerge.org/
MS Access: does everything quickly, and allows easy migration to a more powerfull back-end if required.
Beer helps slow me down. I don't get carried away with perfection, and my mind doesn't race. When the project is working satisfactorily, I can stop thinking about coding, and come back another day with a fresh mind for the next development iteration.
In a .NET environment, the winning trio is:
NDepend is integrated in Visual Studio and Reflector, and Reflector integrates with Visual Studio. http://msdn.microsoft.com/en-us/vstudio/default.aspx
A powerful tool like NDepend  that allows you in a few clicks to visualize the structure of your code. This kind of tool quickly become necessary when the size of your code base is growing. http://ndepend.com
A Kinesys split keyboard and handshake mouse. I quite literally can't do sustained work without something to help my wrists.
A close second is a second monitor. I can use textpad, Eclipse, VS.NET, Netbeans, or any other IDE, but without two monitors, I'm slower.
My hands! Seriously, if there was a mind-reader that can read my thoughts on code then I'm all for it, until then we have to stick with the old fashioned method!!! :)
An Internet connection.
Qt Creator  http://qt.nokia.com/products/developer-tools
My fingers. I have learned to type up to 120wpm with 100% accuracy because of programming, and with that I can make well written, fully documented code quickly.
Far Manager  http://www.farmanager.com/
IntelliJ IDE for me is great! However I have also been starting to use Eclipse!
Eclipse (with PDT 2.x) + Firefox + Firebug
Any editor that has a REL (Read-Eval-Loop) system. Really useful for quick prototyping.
Erm... My brain. And the brains of my colleagues and ex- and current co-workers ;)
Xcode / Dashcode
Omnifocus - I wouldn't know how to manage bugs fixes and slate them for releases without it.
RockScroll  for VisualStudio. Ok so it's a plugin but it's so simple and is such a boost. http://www.hanselman.com/blog/IntroducingRockScroll.aspx
For a serious project, I need a comfortable work environment. Is that a tool? OK, then consider the tools required to create an environment free from freezing drafts, blasts of hot air, and ear-splitting noise. The single most important tool is a proper enclosure - a building. Even on the nicest day, I could only work outside for a short period.
In case the question was referring to software tools, I would have to say some sort of IDE like XCode. Again, this is for a serious project. The most important aspect of the IDE is the ease of access to a comprehensive set of libraries and documentation. XCode is somewhat lacking in the documentation department, but it's usable. Anything less would be impossible.
Visual Studio 2008! :P
git, vim, google and linux
The compiler for your language? Everybody forgets this bit of technology, and yet it is both a spectacular bit of engineering and allows you to completely avoid write assembler code.
My text editor, textpad, from textpad.com for us old skoolers
Eclipse IDE (and its multitudinous plug-ins) - does that count as just one tool?
Maybe not my most used, but when I need it, it's a life saver - DDD http://www.gnu.org/software/ddd/all.png
Look at that picture in the top pane. DDD is indispensable when you have complex strcutres with lots of pointers, lists, etc ...
a picture is worth a thousand curses!
Git for managing versions of your source code
I find Object Dock  to be very useful for my work PC but I don't use it on my own windows machine. Somehow being able to drag and drop any file onto notepad or winzip is very essential. http://www.stardock.com/products/objectdock/
The objective is to finish faster.
Visual Studio and JDeveloper for Desktop EXE
Ruby On Rails for websites
Microsoft Access is fast too.
That's all! Thank you.
Brain, Pen and Paper just like Edsger W. Dijkstra . http://en.wikipedia.org/wiki/Edsger_W._Dijkstra
For webdev Coda on OS X. For 'proper' .Net dev Visual Studio 2010 + MSDN For 'proper' Java dev Eclipse.
Visual Studio 2010 with Resharper 5.0
Can't have one without the other!!
UltraEdit  for your hex editing needs. http://www.ultraedit.com/
Code::Blocks  http://www.codeblocks.org/
The Apple Developer performance tools such as Shark, Instruments, etc. Incredible tools.
CMake  and SciTE. http://en.wikipedia.org/wiki/CMake
1) Google Code Search (saves me unbelievable amounts of time)
2) ThinkingRock (http://www.thinkingrock.com.au/). It's a free tool that allows me to create my todo lists using the GTD ('Getting Things Done') system. Initially I thought it was overkill (compared to my trusty paper and pencil) but I've kinda gotten used to the system forcing me to think through my task rather than just taking a crack at some random task that's been floating around in my head.
3) GOOD sleep. I've often been stumped by design decisions and slept on them only to wake up with the "Oh that's just so obvious" thought.
IPython  - "The goal of IPython is to create a comprehensive environment for interactive and exploratory computing." http://ipython.scipy.org/moin/
I'm Java developer and I love Maven  http://maven.apache.org/
and depending on the work some good music to hold the noise on a low level
Notepad++, visual studio 2005/2008
Vim + Google
absolutely eclipse is my favorioute development tool.it has the best plugin support ide within ide's i used before(visual studio,kdevelop,anjuta,vim,emacs,.if you look at yoxos site you can have idea about plugins.but other IDEs have good features too if i make sorting
launchpad.net  http://launchpad.net
Eclipse with Flex Builder installed.
ViEmu for me. Combined with Resharper and Visual Studio, it's incredible.
bzr. It's amazing.
Any modern IDE. Where would I be without one? Not sure I'd even remember System.out.print()...
I am going to have to go with my computer on this one.
After that, and on a more serious note, I'd have to say the community we work in. I know I couldn't get much done without other smart, inventive, saavy, and helpful people to bounce ideas off.
Notepad++ - advanced free text editor with lots of functionality;
VisualSVN Server as SVN server
RapidSVN as SVN client;
DebugView for capturing System.Diagnostics output.
Reflector for inspecting managed libraries/applications.
Intellij IDEA and Eclipse as IDEs for Java;
For the moment, I think R# is really slowing down Visual Studio, will not use it for the moment.
And finally Visual Studio 2008 SP1. Could not live without it.
Instead of using VS.NET for testing some pieces of code Snippet Compiler is the best http://tech.wowkhmer.com/post/2008/10/29/Compile-and-Test-NET-Code-Snippet-Without-Saving.aspx
So while very new to myself, PClint  is my new favorite. I'm still in the market for a good editor though which ultimately SHOULD be my favorite dev tool. http://www.gimpel.com/
BBedit from Bare Bones
(Or is that considered hardware?)
Favorite development tool?
Visual Studio 2008 SP1 is the bees knees.
Technically, tools that cost money should not be considered as answers. You can't beat the infinite value of free tools.
Visual Studio by far. It works, bottom line. I've used a gawd awful amount of IDEs for different languages, platforms, etc before, but nothing puts everything so nicely into one package -- yet simple.
It's like a car, you can have all the bling on the outside, or you can have it under the hood. Visual Studio puts it all where it matters, under the hood -- where you can tweak it and have it do what you want it to do, and its not just some shotty thing that looks cool.
I tried Resharper, but found it a little odd. I guess I have gotten used to Code Rush and the way it does things.
Resharper is also my #1. I also couldn't get by without TestDriven.NET. SlickEdit's free SlickEdit Gadgets for Visual Studio also adds some nice formatting options.
Source control is a must. I use SVN on a Linux server, but if you have a Windows server, check out the free VisualSVN Server and buy the VisualSVN source control plugin for Visual Studio.
vim and plt-scheme, my all-purpose, cross-platform time-savers.
cscope , definitely. It makes it far easier to work in a large codebase where multiple developers focus on different areas. http://cscope.sourceforge.net/
Charles proxy analyser
My keyboard (unless I want to code with the On-Screen one!)
For XML related work: oXygen  http://www.oxygenxml.com/
komodo  for python development
visual studio for C++ development http://www.activestate.com/Products/komodo_ide/index.mhtml
tortoisesvn and vim....
If you have to do web development for IE, Visual Studio Web Developer. The script debugger is MUCH better than the standard debugger for IE.
VS2008, Firebug, WinMerge, Reflector
My favorite editor SXEmacs (http://www.sxemacs.org), but I extend this to any Emacsen.
Subversion for sure. Any other tool i use is replaceable, but I need subversion to keep everything organised.
No one's said Textmate yet? That, and Firebug.
I use the heck out of HTML-Kit (http://www.htmlkit.com/) which is a Windows based HTML Editor that allows the use of plug-ins to make use of language specific templating and help files.
It also integrates nicely with external help such as the PHP online help.
BlackBox  http://www.oberon.ch/blackbox.html
Eclipse, but Ultraedit comes good second.
Other than a compiler, I'd have a hard time without Toad for Oracle.
vim, bash, svn and opengrok (of my workplace's source code base)
Probably my text editor... (that's SciTE). I can use another, of course, but I always pester not to have my favorite shortcuts.
I dont think there is any one I couldn't live without, or be lost without, as there is a replacement of some sort for pretty much everything. Obviously some are better than others. If i had to answer the question as what would pain me the most to live without, it would be...
VS.NET IDE and Resharper.
I consider them almost a package as one since they integrate so well.
I think it depends on the language you're using. Though, language independent tools such as Google are extremely valuable. Another excellent resource is a site like this :)
IPython , the last Python shell you'll ever need. http://ipython.scipy.org/
Visual Studio 2005/2008 Editplus - Simple yet Powerful www.google.com
For .NET development: Visual Studio.
For Java: NetBeans.
For general development: good music.
Eclipse for Java
VS2005 for .NET
Vim for simple text/xml editing
MSVC 6, for c++/c/erlang/perl/freebasic
For GUI creation I use Netbeans' Matisse.