Nintendo Virtual Gameboy
The Virtual Boy is a RISC-based 32-bit system, which produces high-resolution red 3D images against a deep black background using two mirror-scanning LED (Light Emitting Diode) displays. The 3D experience is enhanced through stereo sound and a new specially-designed, double-grip controller that accommodates multidirectional spatial movement. It is powered by either six AA batteries or a seperately sold AC-adapter.
The system does not have a full 384 x 224 array of LEDs as a display. It uses a pair of 1 x 224 linear arrays (one per eye) and rapidly scans the array across the eye's field of view using curved spinning mirrors. These mirrors rotate at very high speed (they are what produce the mechanical humming noise from inside the unit) and can be damaged if the Virtual Boy is hit, knocked over, or used while in rough motion (such as in a car). A full-size display, while mechanically simpler, would have increased the Virtual Boy's physical size and unit cost to the point where the system would become uneconomical. [source]
For more info visit:
http://www.virtual-boy.org/