MIDI support for Android, over Bluetooth as well as USB, including a Fritzing project that defines a simple Bluetooth MIDI interface. Detailed discussion at http://nettoyeur.noisepages.com/.
Acknowledgment: The implementation of the USB driver was done from scratch, but the idea of writing a soft driver in Java came from Kaoru Shoji's USB-MIDI-Driver (https://github.com/kshoji/USB-MIDI-Driver).