As far as to-do lists apps go, I rolled my own by combining a TextMate bundle with a few Ruby scripts and some keyboard triggers using QuickSilver. If you have a programmable text editor and are a programmer, this is a powerful way to go.

I also turned my TextMate into an editable wiki. TextMate bundles are pretty powerful. Because my wiki is basically a collection of text files, I can easily read them on-the-go using my DropBox iPhone app.