Ok here's an idea.
Who defines music genres? It seems like we all pretty much agree on genres... but who said that if it sounds like X then it's country, or if it sounds like Y then it's electro.
That genre classification only gets you one piece of information. What if we defined genres based on our personal preferences, and the preferences of those we agreed with. Who would be interested in checking out music in the Gary genre, or the Gwen genre.
If we cross-index across those genres we could probably come up with some pretty interesting results.