I say something that stores in the trunk or glove box (doesn't have to be tiny) can be hooked to a cd changer if one would ever want to (may on the way home from the cd store or if a passanger just HAS to hear something you don't have ripped yet). This would be hooked up to a dash mounted big color LCD or plasma touch-screen. It would integrate with after market radar detectors, GPS/Nav and the car itself (the screen would display fuel remaining and other car info.).

Or, if the hard drive had to be stored in the dash, it would connect tothe amp via optical or ethernet connections. Have you guys seen the new "live concert IP networking" stuff out? Guitars, microphones, keyboards, etc, now have ethernet jacks on them. Hook that up to a compatible mixer and the second you plug it in, it knows what the wire is hooked to because of the unique ID and can load a pre-set profile for that instrument. No need to even label wires! Of course, this would require the whole aftermarket audio and car makers to agree to some protocols. Using RCA's, car audio is stuck in the 50's. Live concert sound is at least up to the 90's now with IP networking.

Getting a bit off topic but...