MTV unveiled an online, interactive music guide designed to help viewers learn more about the music they hear on the various MTV channels. is a real-time listing of all the music being played on every MTV show and every MTV channel. This includes the short music clips heard as the soundtrack for such shows as The Hills and The Real World. The guide will also keep archives of all songs played as of today's launch -- providing listings by day, show, and time -- as well as a look ahead to what songs will be played in the next 24 hours at any given time.

Going further, MTV will allow viewers to play 30-second clips of each song discovered via the guide, as well as link through to a more robust artist profile page, where fans can listen to songs in full, view music videos and see other details about the act.

MTV is positioning the Soundtrack site as a music discovery tool first and foremost, touting the 1,500 songs featured in its shows every week, not including music videos, across all channels.

"We are playing more music than we ever have in our entire history," says Amy Doyle, senior VP of music and talent.

But MTV is also angling the site as a forum for new artists to promote themselves. Artists will have the opportunity to create their own profile pages, where they can upload as much music as they like for fans to stream, post videos and promote upcoming events. A soundtrack ratings system will rank artists and songs that receive the most votes from fans on the site.

These profiles are open to all artists, not just those with music currently airing on MTV. The company says its music supervisors will monitor the rankings, and in some cases may decide to place certain songs on air if they receive enough votes.

Exactly how music is streamed from the service varies by artist. Indie and unsigned acts can choose to have their entire album available for full-song streaming, so long as they upload their music to the site. Songs by major label acts will be heard, at first, by streaming the music video - which MTV has licenses to stream.

In time, MTV will incorporate the Rhapsody backend service into the site so users can stream any song in full, with a limit of 25 songs a month for non-Rhapsody subscribers or unlimited plays for members.

And as MTV adds links to Rhapsody's new MP3 DRM-free music store, all songs featured in the site will feature buy buttons as well.