Songlink - Share music with anyone.
FIEND.fm - "Hot or Not" for music discovery: 2 hrs of tracks in 2 mins
humit - A social networking app for music sharing and discovery.
Pacemaker - Create and share mixtapes with friends
aux.app - A free web-based music platform to play music from other popular online streaming services.
Boil the Frog - Create a seamless playlist between any two artists