That's pretty cool.

A few years back I had an arranger keyboard and I hooked a midi controller up to it that could send the different (basic major and minor) chords of a key to the arranger, which would play an arrangement for that chord. It was actually pretty cool because it was like controlling a full band, but I found myself concentrating more on my foot hitting the right pedal for the right chord more than my playing... it was basically too much.

But fun.