I've got an old Palm Pilot Pro that I'm using (nowadays) as LCD Screen for my PC.
The program for the Palm Pilot Pro, is the palmorb1.1_alpha (which is modified for "different" resolutions) and as a LCD server, I'm using smartie that is referenced in the same page as the palmorb...
It works very nice for me... I can read the Download/Upload ratios, change the current song in Winamp, view a spectrum analyzer, etc... without switch-on the main VGA screen.... the only bad thing is that the Palm Display is in B&W, and the backlight is a little bit poor... but it's free for me. And of course... you can use the touchscreen, and assign functions to the "on-screen" keyboard...
Just got it working for myself. Very nice. I may have to scrap the whole membrane switch panel/microprocessor/relay card idea I was thinking about.
Maybe I can capture the output from the palm's keyboard and use the commands to use the relay card. That way I wouldn't need the computer on all the time to use the relay card. For that matter, anything could be controlled over the serial link.
2000 Subaru OBS
Dell P3 @ 900 Mhz
7" Lilliput TS w/DigitalWW in-dash mount
80GB External HD