I have spent the last couple years working on a MIDI guitar project based on the JM128 and MQX. It has turned into too much for just me to work on and I am now looking for collaborators. If anyone is interested in working on this project with me, I can provide dedicated project boards for development.
The project is running but needs lots of work (the concept is patented in the US). The input is a plastic five/ten button USB guitar controller, where each button is preset to a guitar chord, allowing a simple way to learn basic guitar playing. The JM128 acts as a USB controller host, maps the buttons to chords and sends the appropriate MIDI data to an external guitar synthesizer.
Areas that need work are: bootloader for field upgrades, MIDI file player, basic code review.