Have a look at the projects over at Benthack, if you like circuit bending you will get a kick out of the projects. If you don’t know what circuit bending is you soon will.

“A friend gave me an old master keyboard, the roland pc-200. i decided to transform it in a keytar, a strap-on keyboard. i’ve used two guitar/bass knobs for strap and two buttons (bending up and modulation) and one swich (for permanent modulation). it’s easy to do bendings with the joystick (even if it has no neck like other keytar) but with the button it’s nicer.”