Spotify - Map shows when two people play same song at same time
Replayify - Create playlists from your most played Spotify tracks
SoundCloud - Enjoy music & follow favourite artists
Jott - Fast, local, linked notes
Last.fm - The world's largest online music service. Listen online, find out more about your favourite artists, and get music recommendations, only at Last.fm
Kindrd - Discover connections between music, movies, books & places