My MIDI Tube Screamer now has its own custom controller...
OK - it isn't an entirely serious attempt to develop a stomp-worthy, road-ready device - its a GUI-based application for the Raspberry Pi computer. But it works real well and was an interesting learning exercise for me.
There's the full story and full code listings for object-oriented MIDI Control software on my blog:
http://m0xpd.blogspot.co.uk/2013/01/midi-controller-on-rpi.html (http://m0xpd.blogspot.co.uk/2013/01/midi-controller-on-rpi.html)
m0xpd