What's the best Task Manager or To Do List (Software or Web)

If you are running linux, “Tasks” and “TaskJuggler” are both included in the repositories of Ubuntu as open source freeware; both of which claim to be able to meet your needs.

http://www.rememberthemilk.com/
This webservice can also be used off-line and has also some integration with Gmail.
A lot of different ways to add tasks get notifications and group tasks.
Also sharing tasks or groups of tasks is quite easy.
Hope you like it…..

There are many options available; here is a list of five good ones that were selected by people who are very much into Getting Things Done:

http://lifehacker.com/399985/five-best-to+do-list-managers

Gmail now has a great task application built in. And since it’s built in, it will send alerts when a task is due.

http://mail.google.com

It probably seems old-school, but pen and paper won the survey in the 5 Best To-Do List Managers link barumonkey referenced.

I use Gmail’s built-in to-do list, in combination with GTD Inbox.

ToDoist, in my opinion is better than Remember The Milk. I like the design better, plus the Firefox add-on is great. There’s a lot going for this web app.

Toodledo is good for a web based solution. It’s very powerful. www.toodledo.com . These days I’m old school, use a pen, marble composition book and follow the autofocus rules: http://www.markforster.net/blog/2009/7/28/the-revised-autofocus-system.html