I like how pandora and last.fm recommend music based on the genre and bands you’re listening too, but I’m envisioning a site based on literal connections that bands have.  I think the interface could very pretty and fun.  It could be like TheyRule.net.  Think a colored red circle with "Foo Fighters" written in the middle.  clicking on it would pop out all these little circles.  Maybe one would be a blue circle with "Nirvana" written on it.  You could click on the line that connected the two and it would tell you that Dave Grohl played drums in Nirvana and is the front man for Foo Fighters.  Maybe another Circle could be Gary Numan, and the connection is that Foo Fighters covered his "Down in the Park."  Getting content would be as easy as partnering with last.fm, http://www.coversproject.com/, and maybe freedb.org.  I’d like to see connections such as band members that have the same birthdays or went to the same highschool and bands that have the same lyrics or song titles.