I've been using Silverkeeper on my Powerbook for a while, nice and free:

http://www.versiontracker.com/dyn/moreinfo/macosx/14521

Does the job well. I just monted a volume when i made the backup set, and now when i run it it mounts automagically and backs up. Slick. I'm sure you can script it to do all kinds of goodies too.