Well, not sure if anyone would be interested, but I came up with a fairly simple device (only needs 4 ends to be soldered, and 3 parts that can be found at any electronics store, and a simple car adaptor that you might already have, cost me $15.00 w/ the adaptor), and software for the computer that runs it. For automatically shutting down when the car turns off all you need is the device and the software, and for turning on you need a motherboard that supports external modem on feature.
The software also has voice recognition (basic commands, play, pause, stop, skip track, etc.), and voice (answers to what day and what time is it). It also saves all settings when the computer shuts down, eg starts playing at the music (this is all using winamp) and position where it was before you turned off the car.
If enough people are interested, and there's enough requests, I might be willing to make it more "official" and sell it, I wouldn't charge more than $15-$20 (this isn't including the device, like I said it is very simple to build, I myself am not an electrical engineer and it took me 10 minutes to do it wiht a simple solder iron).
1983 BMW 733i
Cyrix 166 32MB with MPXPLAY And no display. Player sits on the back seat with a keypad in front. Someday I'll mount this thing for good...
Gathering parts for carplayer v2.0!
I don't have a digital camera handy, so the only "picture" I can really send is of the program, which can't even be seen (it's a taskbar program that has no window, all you see is its icon in the taskbar). As for the device, to get a "mental picture", all it really is is a serial (COM) plug (like the old modems, I bought the encasing so all it is is a serial plug with no wire). On the other end of the plug, where the cord usually comes out of, I put a power plug (like the one sony discmans use, but you can buy any kind at an electronics store and put that back there instead), which is where the adaptor comes in, it plugs into that (you could build your own if your electronically saavy, however I am not, so I figured better bo buy a $5-$10 sony discman car adaptor). On the inside of the device it is as simple as I mentioned, only a resistor connecting to the correct pin and a wire to the other. The program, as I mentioned, is very basic, all it does at the moment is turn the computer off when the car's turned off, save winamp settings (whether it was playing, and if it was, what track it was playing and how much through the track it was, then reloads it and plays on next startup), and basic WinAmp voice recognition. I will probably add more in the future if there is enough interest (DVD playing, GPS, etc.) It also has basic commands (what day is it, what time is it). THe nice thing is although new commands can only be added by me, aliases to commands can easily be added to any user (for example, at the moment all commands have to be followed by "computer", eg "computer play music", however, this can be removed or changed to something else, eg, "baby play music" also, aliases for commands, such as "play the damn music" can be added in addition to the ones that exist, and the ones that exist can be changed/removed)