I'm really, really enjoying this (free) simple browser app To-Do list from SwissMiss. Tina Roth Eisenberg designed the look of the program and then her two studiomates, Fictive Kin, made it happen. *It's incredibly easy to use and has a nice, clean feel so you won't feel overwhelmed by all you have teaux deux! I made it my home page, so I can just click over anytime.
*They are working on an iPhone app, as well.