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.
The Best Song - The fun way to discover good music
Musicroamer - A visual Pandora for discovering new music
FIEND.fm - "Hot or Not" for music discovery: 2 hrs of tracks in 2 mins
LivePlasma - Discovery engine map for books, music, and movies