AKA: Distributed Moderation
Collaborative Moderation ("many eyes") is a concept known under various names and used in diverse ways. It is a concept whereby the efforts to ensure quality in an item are distributed among many people. Collaborative moderation occurs when two or more people determine what information other users with similar interests might prefer or find relevant to the context of the dialogue.
Slashdot uses the term "karma"
Typically only a relatively small percentage of a website's users are willing to moderate comments or stories, so a site usually has to reach a certain size for collaborative filtering to become useful. The percentage of active moderators could be increased if latency issues could be resolved: Usually, you have to load a new page for the moderation to take effect. Moderation also requires identifiable accounts, but it may be hard to motivate users to create such accounts if the ability to moderate is the only incentive for doing so.