HotMusic - HotMusic is the best music service to discover songs from your favourite genres RIGHT AFTER their...
PlaylistMap - Connect with Spotify playlist curators from around the world
Tune My Music - Transfer Playlists Between Music Services
Undrtone - Social layer on top of Spotify and Rdio from Scott Vener
SoundCloud Charts - The most played tracks on SoundCloud this week
Spotify - Map shows when two people play same song at same time