TeuxDeux (pronounced "to do" duh...) is an awesome and brilliantly named, if I may say, web browser-based application designed by Tina Roth Eisenberg A.K.A. SwissMiss and developed by Fictive Kin. What TeuxDeux basically does is allowing you to list the things you need/have to do in a day (or sometime in the near or distant future) in an absolutely "ordinated", yet flexible and perfectly simple manner. You can move things around, mark them as done and delete them.
Already loving it. Now if they throw in an iPhone app and/or a Mac application they should be heading towards an innovation Nobel Prize... at least in the designers/creatives parallel realm, for redefining the term "To Do".