Auxy Music Studio - Auxy brings real music creation to iPhone in a simple and inspiring format.
Netflix Party - Netflix Party is an extension for watching Netflix remotely with friends and family for movies nights with that long-distance special someone.
Sampulator - Make (and record) beats on your keyboard
StreamParty - StreamParty is a watch communiry, that allows you to watch video streams in sync with the people you care about, on multiple services.
Ramsophone - A generative art/music machine. (Be sure to refresh!)
Metastream - Watch streaming media with friends