FreeBrie is a distributed decentralized backup and file synchronization system that can be used for free without limitations as long as user wishes.
Usage is simple as 1-2-3: install the client (for MacOS only; Windows and Linux versions coming later), decide how much of your hard drive you would like to share in exchange, and start enjoying its benefits!
In private beta now; please signup at http://freebrie.net to receive the invitation as soon as the public beta is started.