Remember the Milk ^[1] is my favourite.

Gmail has task integrated into it ^[1].

While it lacks the features of some of the dedicated task management sites, gmail wins for me because tasks are so cleanly integrated with a tool I use heavily day to day.

Toodledo ^[1] is another good web app. It supports also integration with IPhone and IPad using a priced app.

Here it is a features comparison chart ^[2] (provided by them).

Check out Nirvana ^[1]

I've been beta testing it as a clean, simple, yet powerful to-do to manage my teams workload. Closed beta, but fairly easy to get in ... I'd recommend it.

I share your un-healthy love of lists.

I've tried Notational Velocity ^[1], Nottingham ^[2] (both synced to the web via Simplenote ^[3]) Apple Mail, Outlook Google Docs ^[4], etc, etc.

But by far the best solution I've found is simple, plain text (or Markdown ^[5]) files, synced to the web via Dropbox ^[6] and edited on the web via Droptext ^[7] (App store link).

Syncing a file based list is much better than using a pure web/iPhone app, as you can also work on the files offline. Moreover, you can use your favourite text-editor to edit and organise your lists.

(It's a popular question this - the same question has been asked ^[8] on gadgets.stackexchange.com)

I am a big fan of 37signals Ta-Da Lists ^[1] there is also a handy iPhone app as well! It is also 100% free.

todoist.com- good interface, good design

Remember the Milk ^[1] is my favorite by far, but the only other one I have really used is Google's in Gmail. I started using RTM when it started and I have never needed another solution.

I use ToDoList ^[1] with dropbox. (after testing many systems...)

I use Producteev ^[1], its very fast and well designed, have several workspaces, support tags, task delegation. Allow create you task mostly from everywhere, by using email, icq, etc. Application allow sync with google calendar. Very nice web application with extremely simple and beautiful interface.

You should check http://dddone.com, especially if you're a programmer. It has a unique approach of representing a single todo list in two ways: sorted by priority and structured as a tree - all on the same screen. Very convenient.

A couple of low tech suggestions.

• Use an email folder in your email client.
• Text file saved in a Dropbox.

I use Reminder Fox ^[1] Add-on of firefox. Its pretty good.

Try the new coolendar.com ^[1]. It's html5 + css3 and pretty well designed.

I'm using Weekis ^[1] and liking it a lot. It's minimal and unobtrusive.

I've been using Vitalist ^[1].

How has reqall ^[1] not made this list? You can add a todo item via email, im, text message, voice, and they have pretty good input recognition to pick up on keywords, times and dates from your items to organize them as you go without you having to manually configure when the item is due.

Im also an TeuxDeux fan, but I still think you should check out http://www.thymer.com/ its great and have a lot of features but still very clean and simple.

tadalist ^[1] from 37 signals is my favorite

ManyMoon ^[1] is an oddly-named, full-featured single- or multi-user (collaborative) task system. Add tasks, assign to users, send emails of tasks, attach google docs, add comments, tags, statuses, etc.

It also has integration with GoogleApps, if you're using a hosted gmail solution. If you're not, well, then. Start up tasks the old fashioned way.

It's the best free collaborative task system I've found. I probably prefer the uncluttered interface of Basecamp, but you can't get that for free.

I've used Good Todo ^[1] by Mark Hurst, it's pretty good.

I'm using the amazing Tracks ^[1] - open source, aGPL, ruby on rails, easy to extend and comes with an api. I used the api to knock up a quick email to tracks bridge ^[2]...

For just quick notes and todos while I'm working in a project context on the command line I use ditz ^[3].

Nozbe ^[1] is my favorite way to Get Things Done ^[2].

Check out Pivotal Tracker ^[1] - its really geared around iterative design but you can use it for many things. It has slick real-time collaboration, a killer interface and is completely free.

I use Evernote ^[1] with a todo tag. Less than ideal, but I somehow like it better than Remember The Milk and use it to store my non-todo notes already.

I've been using Hiveminder ^[1] for years now. I've tried most of the popular TO DO apps out there, but I keep coming back to Hiveminder. Its "Braindump" box lets me enter a bunch of tasks quickly, and the "Task Review" process helps me prioritize and categorize my tasks inbox easily. The user interface is very clean and fast. There's also an iPhone app (iMinder). I think Hiveminder is a great undiscovered gem.

Checkvist ^[1] is nice and simple and you can use your keyboard which really speeds things up. It's almost as easy to use as pen and paper.

Paprika ^[1] is nice and simple with good usability, and it integrates plaintext notes with a todo list and tags. It's useful for storing information along with the todo list.

I use DropBox ^[1] and TodoPaper ^[2].

37signals BackPack ^[1] is like a beefier version of their Ta-Da Lists ^[2] that Jeff Epstein recommended. It adds collaboration, notes, multiple pages, and a few other features.

I like Springpad ^[1]. Has some todo list like functionality but is really more like an online notebook. It adds some really useful extra information to the stuff you put in it.

I've recently switched to the more simple, yet powerful, Todo.ly ^[1]. Todo.ly is very lightweight and user friendly. It's missing a few nice-to-have features, but overall it's my favorite Todo app.