I think Arq (http://www.haystacksoftware.com/arq/) seems like a particularly useful program. Wasn't aware of it before. I like how they give you control over your backup storage.
I've used Arq for about 4 months now and it has been fantastic. Two features in particular are worth noting: 1. The ability to backup a network drive from my local machine. 2. Rapid timecapsule like backups of the most recently used files.