Tempso - Finally a place for classical music online!
Magic Playlist - Get the playlist of your dreams based on a song
musicForProgramming(); - Mixes intended for listening while programming
Spotalike - Spotify playlist with similar songs, according to Last.fm
Music-Map - The Music-Map is the Tourist Map of Music, part of Gnod, the Global Network of Discovery.
Spotify - Map shows when two people play same song at same time