From Music Hack Day

It's live, check it out. And it's fully functional! http://callaboraoke.com/

[edit] Concept

1. A call for collaborative karaoke!!
2. Friends collaborate on singing songs.
3. Songs are broken up by lines.
4. Users sing along and are recorded over the track on the phone.
5. Songs are stitched back together and notified when ready.

[edit] API Integrations

1. MusixMatch
   1. Pulls lyrics data with timing information.
   2. Cuts up an mp3 into pieces based on who is participating, and the timestamps.
2. Twilio
   1. User enters phone number and it calls the user to record their part of the songs.
   2. As the user record pieces of the song, the lyrics page is updated in real time.
3. echoNest for pulling artist images
4. In the middle of SoundCloud upload integration