Its kinda odd how you go from nothing to something. But after seeing this thread, and threads on other car sites I frequent I've decided to take the plunge! I now have a 7" widescreen VGA touchscreen monitor, and a Mini-ITX motherboard running at 800mhz. Its still being set up, but will be going in the car in a few weeks. Heres a pic:
I also have Wi-Fi, with GPS coming sometime this summer. It will be mounted in my airbag compartment (pass side), and the screen will be mounted to the ceiling in front of the sunroof. All running into my headunit and controled with a timed shutdown controller, and a small DC-DC 120watt power supply.