We have five of the little 5.6" TFT screens we collected off of eBay for use in portable DVD/VCR system we have (Audiovox/ Eddie Bauer). If you shop around, you can find these for less than $50, with composite inputs, and stereo speakers. They run on 12vDC.This online reseller
offers a nice range of little screens with even more
functions... depending on your needs: TV tuners, remote controls, some even w/touchscreen USB and VGA connections. A computer geek could make something really cool with a mini computer and one of those monitors... combo video/MP3 player, GPS system, multi-camera viewer/ recorder... combine w/ an X10 system, and you have some nice automation for your AC items.
Google the term "mini ITX" and you'll be floored by the tiny little PCs folks are building. Some are even integrating them into their automotive systems, so a bus would provide even more areas to innovate.
Geek's the limit...