Lately, I have been getting lost in Marshall's amazing world of circuit bent toys, homemade circuits, and instruments. Really. Check out "Sample 1" from his custom Playskool Old MacDonald keyboard. Custom, as in set up with:
Body contacts, 555 pitch control (w/ on/off), triangle wave pitch modulator (w/ on/off), LED to show triangle wave's rate, 2 distortion switches, 1/4" output, kill switch.
"Sample 2" is also great. There's like a million other good tracks to check out, so get to it.