MEMS - Stands for Micro-Electro-Mechanical Systems, and are a trend in device manufacturing beyond eletronics. As the name says, we are talking of devices like computer chips that include also mechanical parts and optical parts.

Todays uses of MEMS technology seens to focus on creating optical devices with a tiny mounted mirror, that can project light in any direction, really fast, thus being able to function as a screen, by projecting this image in a surface, or even in one's retina.

Existing retinal projection displays using MEMS IC's exist today (6/2002) and are priced at a U$15000 tag. One of the main corporation working in MEMS production and fabrications is Microvision. You can read more about MEMS on their site at:
http://www.mvis.com/tech_more_mems.htm .