We just finished getting our backup server running-- it's just a cheap server (a mini-ITX, actually-- we paid extra to get a cute one we could hide in a table lamp, so it's not the cheapest server on the market) and my programmer's writing a script to automatically back up all files on both of our computers every night. It's got a 160 GB drive, which ought to suffice for now.
I don't think it needs to be a terribly complex solution. And I don't have an off-site data storage solution worked out, so if the worst should happen and my home be damaged, I'm out of luck. So that's a good idea, sure. I might periodically burn the irreplaceable stuff to DVD-R and stick it in my desk drawer at work, but that's hardly professional.