There is a company that I read about at CES that I thought I would like to highlight. Its called MicroOptical, and they make ultra portable wearable displays that you can wear on your glasses.
I have been a big fan of wearable computers for a long time, but have seen them as very impractical, because the display and the hardware was much too bulky. I have watched this equipment shrink in size over the years, and have seen the capabilities increase to a point where its becoming more practical.
The MicroOptical head-up displays are very small, and light (they weigh about 1 ounce), and can accept standard VGA, NTSC, PAL, RS170 and RS-232 signals.