The I-MU Vibro Speakers ($100) might have a somewhat kinky name and design, but they (also) have quite a cool feature.
Stick it on your desk, fridge, car bonnet, or pretty much whatever, and they will turn the surface into a high quality audio speaker (Output power: 30w).
The main component is a tiny piece of a material called Terfenol-D, which was originally used by the US Navy for sonar work. The Terfenol is placed within an aluminium case and a coil wrapped round it. When electricity is passed through the coil the Terfenol expands slightly creating a massive force of 400 pounds – when its attached to a flat surface it transmits electronic signals into mechanical energy causing the flat surface to vibrate and broadcasts the sound.
Cool…