Peer moderation for forums
As forums grow they will become increasingly vulnerable to spam or message flooding attacks. Peer moderation is a mechanism to promote the spread of messages that forum members consider to be worthwhile.
Voting on which messages are worthwhile and using a global tally of votes to decide which messages to approve is not secure in a fully distributed system due to Sybil attacks. However, each peer can decide which messages to propagate based on the votes of its owner and the owner's contacts, which are not subject to Sybil attacks.