I just circuit-bent a cheap Yamaha keyboard and it's extremely exciting.

Was it hard? What did you do? I've got a little Cascio I'd love to fuck with.

Yes! More info please, because I'm fascinated by this sort of stuff.

It's very easy. First get two of those all-metal precision screwdrivers and clip them together w/ alligator test clips. Open the keyboard and flip over the PCB so all the little contacts are exposed (and all the physical components are on the reverse side). Now turn it on WITH BATTERY POWER because if you try circuit bending a plugged in keyboard you'll severely damage it and/or yourself. Now turn it on one of those stupid built-in rhythms so that it makes noise w/o you presisng keys. Now uhh just randomly touch two contacts together with the screwdrivers. With my cheapo keyboard 99 times out of 100 the circuit will crash and you'll have to turn the keyboard off and on again, but with a lot of patience you should find some really crazy sounds. My experience comes best between connections coming from the CPU to some sort of component (like a resistor or disc capacitor). And if you have an FM chip it's supposed to be an endless array of sounds. Try to stay away from the power supply part of the board. And if anything sparks, don't do it again. And whe you find a thing you like, just get a switch (SPST or SPDT) and wire it up.

Oh and read this.http://www.oddmusic.com/illogic/illogic1.html

this is great fun! i bent a speak n spell (kinda 101 for circuit benders) and a casio sk1 a couple of years ago. the speak n spell one is great fun if you try to play one of the inbuilt games, demanding "SAY IT ........ zzzzZZZZZqqqSTdfgDF ....... SAY IT ...... zzzzzQVCsdfsYW" in a martian robot voice.

I hear with SK-1's, there are so many working bend ponts that it's not a matter of actually finding them, it's a matter of picking like 7 or 8 that you like the best (or however many you have switches for)

Make Magazine ran a great article/podcast on beginning circuit bending. Check out:
http://www.makezine.com/blog/archive/2007/01/circuit_bending_3.html
http://www.makezine.com/extras/32.html
http://www.makezine.com/extras/33.html