TimofSuburbia has a post of literally dozens of Pandora hacks and mashups. It also looks like he has created a cool Digg-like interface and station directory. I few weeks a ago a played around with the same idea for Shoutcast stations using Ning, but never got very far. I'd love to see someone (who knew what they were doing) pick up on this effort.
He has also got a separate wishlist for Pandora features that you can vote on. Great stuff, check it all out.