My setup is via the Alpine products.  I have a CDA9831 CD player with the Alpine KCA-420i I Pod interface.  Using this setup the CD player accesses and fully controls the IPod as if it were and enormous music library.

  I have the 420i up under the dash and the cabling plumbed into the glove box.  Now here is the hi tech part.  I keep my I Pod in a running sock in my glove box discreetly hidden under glove box junk, who wants to grab a nasty ol' sock to see what's in it ;-)

  As for functionality, I'd give it a 10 for sound and integration and about a 7 for functionality.  Tryin' to surf through 20 gig's of music is tough without having time.  You can't go directly to an album or artist without scrolling, so creating well thought out playlists is the answer ~ lot's of playlists.

  Lastly, I ditched ITunes.  I'm a WinTel based computer user and got sick of not being able to move music up AND down off my IPod.  I did some searching and found a product by Media Four http://www.mediafour.com/products/xplay/ that does everything ITunes should have done.

  Anywho, that's my setup
  Brian