Nothing at all except I am hoping for the ability to edit stuff while in the car, i.e. writing stuff without mounting disks rw. This would be extremely useful if someone got an IR keyboard working, but would also have some other applications...

Right now my selfish reason for wanting the ability to write to the HD in the car is so my lyrics scroller could be pre-loaded with a bunch of text lyric files, and the user (passenger obviously) could generate timings for them while on the road... Each line of the lyrics would be displayed, and when the player got to that line in the song, the user could click a button. This data would, of course, not be immediately written to the ID3 tag, but could be parsed and written later.

The OBD-II stuff is another area where we could use the ability to write to a custom HD partition. I'm sure we can think of many other neat applications, like recording a log of GPS data while driving (I'm sure many of the GPS units themselves provide this, though.)

All in all I think it'd be a very neat thing to have. I realize you're overloaded right now with more worthy tasks, so hopefully someone out there might have the knowledge and the desire to make this happen. I have the desire, but not the knowledge... yet.