MacDevCenter.com: Flexible OmniOutliner. OmniOutliner was one of the nicest surprises to find bundled with my PowerBook, and it may end up replacing wiki as my way of organizing notes and other information. I've played with outliners before and have been charmed by the idea. It was nice to find a decent one sitting on my hard drive.

If you're using the version of OmniOutliner that came with Panther, you might want to upgrade.