Last September, Doctor Kristen Stubbs -- a roboticist who makes sex-gadgets for her Toymaker Project -- released a video (NSFW) demonstrating her prototype pelvic-floor strength-tester, called "The Hammer." The Hammer has a bulb that is internally inserted, containing a squeeze-sensor, and a penis-shaped, light-up readout that protrudes between the wearer's legs. The harder the wearer squeezes, the more the readout lights up.
Right now The Hammer has two modes: the test-your-strength game, where the more you squeeze, the more it lights up; and a demo mode which cycles through all of the colors of the LEDs. Soon I hope to connect the Arduino to my Android phone, and then I’ll be able to do even more cool things!
I’ll be following up on this with more technical details over the next few weeks. (Update, 10/11/12: If you would like to hear me talk about how I made The Hammer, you can see some excerpts and my slides from my technical talk at Arse Elektronika 2012.) My plan is for The Hammer to become an Open Hardware project. This is still very much a prototype, but I would be thrilled if anyone else wanted to build their own.