P2P online backup
Very rarely you see an online ad that is interesting.. Today I noticed one for CrashPlan.
They offer both a free and paid online backup solution. The interesting thing about the free version is that you back up your data on your friends' or family's computers (rather than a central remote server). Quite a novel approach. About the only downside is that the free version apparently is ad-supported. Not sure how annoying they would be.
I think all the computers would need to be online at the same time for backups to work properly. Presumably the same would apply if you needed to do a restore too. Something to take into consideration.
There is also a paid offering too (for orphans or people without any friends?)