I am using a Seagate FreeAgentGo, a tiny portable USB powered external hard drive, to do my take home backups. It can fit into your pocket, about the size of a wallet. I feel powered hard drives are more reliable than flash or "thumb" drives as far as data corruption prevention goes. Furthermore, the FreeAgentGo is 120BG, and they make larger cap ones. This far outperforms even the largest cap thumbs.
I also don't like how easily I lose thumb drives.
Off site backups are a good idea too.
