Momixa - Pick two songs and get the perfect mix
Gnoosic - Even if you don't know what you are looking for - gnod will find it.
Music Suggestions Ninja - Enter an artist's name & find similar, lesser known artists
Musicroamer - A visual Pandora for discovering new music
Boil the Frog - Create a seamless playlist between any two artists
LivePlasma - Discovery engine map for books, music, and movies