[tyng]

The idea of a P2P backup solution is interesting, more so if you can hook up strangers into a massive backup network.

Of course, the challenge is to make sure the peers are online when you need the files, and for this reason the network may need 5-10gb of storage for 1gb of data to duplicate the content across multiple users.

[xur17]

Wuala tried to do that, but I think they have since switched to a centralized solution.

The difficulty is ensuring enough clients have a copy of the file that it won't disappear, especially with people connecting and disconnecting a lot.