CrashPlan automatically backs up to multiple destinations. Its groundbreaking social backup concept makes it easy to back up to computers belonging to your network of friends or family for offsite backup, in addition to using your own computers and external drives for onsite backup.
In other words, if something happens to one of your backup locations, you'll be able to restore from another.
This program works on all your computers, so you don't have to worry about compatibility either.