More references

Jam for iPhone

https://itunes.apple.com/us/app/jam-for-iphone/id580366563?mt=8

This takes voice input, and determines the chords that would fit it and records it along and plays back.  Pretty similar to things we're thinking of.  (essential auto accompaniment that's very user friendly)

Find your way to OZ- music

This is an awesome Chrome music experiment that has a note input interface similar to what we're looking at...

http://www.findyourwaytooz.com/music/


All the chrome experiments can be found here:

http://www.chromeexperiments.com/tag/audio/

chromatik

I've met the CEO, Matt Sandler at the Music Tech conference a month ago.  It's different than what we are doing but still worth to take a look.