Disney Research is apparently developing plastic accessories that can control phones, which might even be more far-out than MIT's thumbnail trackpads. They're called acoustruments, and they can control phones with sounds from their own speakers. How? Well, each acoustrument comes with a U-shaped tube that feeds ultrasonic sound from the phone's speaker to its mic. You can control the phone with that setup by disrupting the sound, say, by blocking holes on the tube like you would on a flute. Its controls don't necessarily have to be holes, either -- they could be buttons, switches, knobs, wheels, sliders and anything else that can alter the sound wave to indicate an action.