I have an old equaliser that I want to use with a Raspberry Pi. The EQ takes stereo input, adds a fader, and a selectable 60/80Hz crossover for subwoofers. 2ch in, 6ch out. It's only 500mV, as the main downside, but I have the information to make it 3.5V. I already replaced all of the TL072 Op amps with Burr-Brown OP2134 chips. the Raspberry Pi should give me almost all of the features that a droid tablet has, plus XBMC for media management. Add in some extras using the GPIO, like automatic shutdown when the car is switched off, and a dock for a portable hard drive for media, and I think I can have some nice stuff.
I have made a car PSU that will take constant power, and accessory power, and alert the Pi when accessory power goes away, thus allowing it to shut down. While power is on, there is 3A available to a USB port. When accessory power is removed, there is a 4 min delay, then all power is removed. This gives shutdown time to the device running on it. (The 3A means that there's enough power to run an external USB hard disk drive for a couple TB of storage.)
I have 2 screens that I'm waffling between. One is a 7.2" LCD, 1280X768 resolution, and the other is a 10.6" 1360X768 resolution. Both can take DVI/HDMI input. The other option is to spend some more money on something that also has touch screen input (Neither of these do at present, but a small touch pad to give mouse input is cheap and can be conveniently located, and a small wireless keyboard would mean that I can do whatever I want.
