Dan's rsync to Disk incremental BACKup utility is a simple bash script driven by easy to edit and easier to understand config files. It's meant to be used with a laptop and an external USB harddrive as the backup media or over NFS to another server
Well, it's been 6 years since I wrote ddback and it's still running great on my Fedora laptop. Overall, I'm happy with how it works and it's saved my bacon a few times. It's no Time Machine with a pretty UI, but it gets the job done with a minimal of effort. Plug it in and away you go.