Recently I've been trying out the Time Machine feature on my (relatively) new MacBook. It's good, but I don't have a huge external hard-drive and can't really justify buying one at the moment. The best I've got is an old 20GB MP3 player that I've formatted.

Obviously, with about 25% the storage capacity of my internal HD, I can't backup everything on my Mac. So I've excluded everything except my documents, music, and any applications that can't be readily replaced if disaster strikes.

It's working so far, but I can't help thinking there's probably programs out there that would suit this task better? Does anyone have any suggestions?