Jukebox - Collaborative music player
WebTube - Lightweight YouTube frontend
Clicker for YouTube - The best standalone YouTube TV player for Mac
LiteTube - LiteTube is an app that provides HQ video and audio streaming players.
Spotify - Map shows when two people play same song at same time
TubeMote - TubeMote is an app that lets you create a channel that broadcasts from YouTube, Dailymotion, or any other portal, and browses channels using your phone anytime and anywhere.