Bandlab - Capture, nurture, and collaborate on song ideas in the cloud
CyTube - Free, open source synchtube
Krue - Twitch for music: live streams from amazing musicians
Metastream - Watch streaming media with friends
Vampr - Connect with musicians, industry & music lovers alike
Watch2Gether - Watch2Gether is an app that allows multiple people to watch the same content simultaneously and interact with each other while watching.