Gibbity

As a participant, you can either explore the current game listings and review stuff you find, or you could contribute games that aren't there yet and review those. That's basically all there is to it (but you're welcome to check out the lengthier description and explanation here, if you've got time to kill.) Ideally, it allows users to quickly find new (and old) games that other users have picked up and enjoyed. Kinda like Amazon.com's review/recommendation engine, except that it's smaller, simpler and doesn't ask you to pull out your wallet every other page-load. Additionally, you can use Gibbity's social-networking functionality to form friend-networks as well as "focus groups" (i.e., groups that focus on specific types of games, or games from a specific publisher).