Spotify - Map shows when two people play same song at same time
Google Play Music Desktop Player - A beautiful cross platform Desktop Player for Google Play Music
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
GDeskTunes - Multi Platform Desktop Player for Google Play Music™ that integrates beatifully in your OS.
SoundCloud - Enjoy music & follow favourite artists
Nuvola Player - Cloud music integration for your Linux desktop.