garagebandGarageband is a really interesting peer-review and music discovery site. Artists submit music to be hosted onsite, which is then sent to 20 other artists, who review it. If they like the song then it tends to rise up the GarageBand chart and get more plays, reviews and ratings. Reviewing songs earns you entry into competitions that the site runs for various prizes, giving a continual incentive to help out other producers and artists with advice and peer review, and provides the opportunity to get free stuff and good press for your music.