Watch2Gether - Watch2Gether is an app that allows multiple people to watch the same content simultaneously and interact with each other while watching.
Wohooo.net - Create Your Own Online Radio Station
Metastream - Watch streaming media with friends
Listen2MyRadio - Stop dreaming, start streaming. Free and premium Shoutcast and Icecast audio broadcasting.
StreamParty - StreamParty is a watch communiry, that allows you to watch video streams in sync with the people you care about, on multiple services.
SOUNDS - Discover music with friends