I'm playing with the idea of putting together a car MP3 system. I can manage the software side on my own no problem, as well as most of the hardware (it's going to be a low-power mini-itx board with a ton of RAM. I'll dump Linux on it and mount the hard drive read-only so it's not a problem when I turn the car off.) At this point, the only problems remaining are connecting the computer's line-out into the stereo system (with luck this is as simple as patching in a cheap amp for a first test, or even just splicing it into whatever built-in radio happens to be in the car) and the big one - power. I don't know how to get a reasonable amount of 12V power out of a car - I know that in theory the car's power system is 12V, but it's not exactly clean power, and unfortunately I know little about electronics right now. (The whole setup would be *very* low-power, considering how much it can do - we're looking at 30w without a CD-ROM, 50w with).
Any suggestions, or pointers to where I can learn more about this?
(There's also the problem of the keypad, but worst-case I can just rip a keyboard apart and rewire some keys.)