I would suggest you check out SmartStim.com. Great electrosex site. I own an ET-312B and originally bought it for the pleasure side of it. I quickly discovered that nice pain/pleasure boundary which is so fun to play around with. Now that I am into BDSM my wife uses it as a torture device on me. It has plenty of power to hurt, very badly, but still not cause any real harm if you follow some basic rules.

There are all sorts of electrodes you can buy for them. The possibilities are endless. Just remember keep it below the waist and do not use it on anyone with heart problems, a history of seizures, or any implanted electronic medical device.