I was flipping through my new Summit catalog and came across this.
The website doesnt give a discription, but the catalog does. "varads racerboy shift knob incoperates four switches to give you thumbtip control of your favorite electronics. Hook it up to your accent lights,nitrous, or other electronics... features built-in microprocessor, which allows you to select from four different activation modes- on/off, flashing, pulse, and momentary. for manual transmissions only"
seems perfect for the car pc. you could control volume, skip songs, gps view mode, etc. I was also thinking it would be pretty cool to map the lilliput and/or xenarc power button to this (the ones without auto on). Just a thought.
or maybe this
or a DIY equivilent