I want someone to create a web app like (or with) Last.fm or Pandora but that allows you to follow a stream-of-consiousness music chain. You select a song or artist and it plays a song by that person. Then it randomly selects 2 "similar" songs and you choose one to listen to next. You could play games to see how long it takes to get from one artist to another. How many steps from Public Enemy to Johnny Cash?