FIEND.fm - "Hot or Not" for music discovery: 2 hrs of tracks in 2 mins
JamBuddy - Find and collaborate with musicians around you thru Spotify
Pacemaker - Create and share mixtapes with friends
Symphona App - Designed to make orchestral staff management a breeze.
Boil the Frog - Create a seamless playlist between any two artists
Undrtone - Social layer on top of Spotify and Rdio from Scott Vener