As I recall, there have been devices in the past that amplify the sound of portable devices using a system of channels as opposed to electronics, but the AirCurve from Griffin is designed specifically to work with the iPhone and the iPhone 3G. No power source is needed—the AirCurve directs sound from the iPhone speakers through a “coiled waveguide” that, according to Griffin, produces a sound akin to a set of desktop speakers.