Separate Audio stream for music on Stream
I think it would be cool if Twitch made it so streams can have music on a separate audio stream and viewers can choose if they want to hear both streamer and music or just the streamer. The music part can be made to all for song requests or interfaced with outside music sources like iTunes or Windows Media Player
I would love being able to have music uploaded in a separate audio track so that future VODs could just have that track muted instead of the entire stream.
And as a viewer I would love being able to turn off the music when watching a stream, if I am only interested in what the person has to say.
I just came to post this. I've left so many streams because I generally work with Twitch on in the background, so I like chill game streams, and its a shame I have to leave because the host is playing dance music or something else that's too distracting for me.
Plus the other benefits of being able to remove the music for VODs too would be a sweet bonus.
Stefan Schouten commented
This will also cause more VODs to be watchable, because they can just remove the separate music stream whilst leaving the streamers voice/game audio intact.