TimeDrawer

Mac OS X only: A lot of us are excited about Time Machine, the new feature set to launch with Leopard that adds built-in file versioning to OS X. However, until Leopard is released (or until you decide it's worth the money to upgrade), freeware application TimeDrawer provides an attractive, intuitive file versioning system for your Mac. Every time you update a document, TimeDrawer keeps track of your changes. You can compare your current document to itself from as little as a few minutes ago to much longer. It might take a little to get used to if you've never used file versioning, and I haven't used it for long enough to say exactly how user-friendly it is, but it seems like it might turn out to be a great alternative to Time Machine for people not eager to upgrade to Leopard.