Epic Pen - A windows tool for drawing over your desktop and applications
Spotify - Map shows when two people play same song at same time
gInk - An on-screen on-screen annotation software for Windows.
SoundCloud - Enjoy music & follow favourite artists
Gromit-MPX - Create annotations by directly drawing on your screen.
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