Skip Tunes - Control iTunes, Spotify, or Rdio from your Mac's menubar
Muzzy - it’s a tiny and gorgeous iTunes companion that lives on your menu bar. For Mac OSX, its free!
Baritone - Spotify controls that live in your menubar.
Spotify - Map shows when two people play same song at same time
Soundiiz - Transferring playlists between various music streaming platforms.
CoverSutra - CoverSutra gives you a handy and attractive way to control iTunes without ever leaving your current...