I've had a Rock Band keytar controller on the shelf in my dungeon for a while that I found for a few bucks at a furniture outlet of all places. For some reason, it puts out regular MIDI in addition to being a game controller - just connect a cord from the 5-pin DIN plug to your favorite sound module, synth, or computer and rock out. I like the feel of the keybed, and it's got octave and program change buttons, and the touch slider does pitch bend and modulation (though it's a bit wonky). It communicates wirelessly with a Wii, but that's only as a game controller. I have a couple XBees from when I followed Lady Ada's very good MidiBee tutorial back when I started all this soldering nonsense in earnest. I decided to crack open the controller and stick an XBee inside, and put the other into a quick and dirty USB MIDI interface made out of a hacked cheap USB MIDI cable and give myself a wireless MIDI keytar controller to rock out on.