To Do Managers: Organize Your To-dos, Bookmarks, and RSS Feeds with Treedolist

Lifehacker: "Web site Treedolist hierarchically organizes your to-do list, notes, bookmarks, RSS feeds, and pretty much anything else you can think to drop into it. At its most basic, you can think of it as a simple to-do list with the ability to add structured and nested lists and then filter your lists by due dates, labels, and a number of other useful methods."