To Do: Make To-Do List (Slate.com) is an article about trying to get organized with Web-based task managers. Ta-Da List gets a mention...
Ta-da List
This is a dead simple manager created by 37signals, the influential Web application company. You create a list (say, "Move to Alabama") and then you begin adding specific tasks ("Hire movers," "Sell snow shovels," etc.). Once you create a task, you can reorder it in the list or check it off as done. That's pretty much it. Ta-da List is free, and it looks great, especially on the iPhone.