I spent a few days researching decks and driving around to shops. I settled on the Kenwood DNX-8120. Top selling points for me were
* Navigation data is stored in memory on the unit (no DVD discs). Maps can be updated from garmin.com
* Has 2xUSB input for a regular thumb-drive, external hard-drive
* 5 volt outputs
* Can play MP3s from a DVD disc
* Built-in Parrot bluetooth works very well
The Pioneer AVIC-Z2 or Z3 looks better and has better menus, but lacked USB inputs, and can't play MP3s from a DVD. The Z2 has a built-in harddrive which sounds great, but you can't copy MP3s directly to it, you have to burn them to a regular audio CD then have the unit rip it into its custom internal format. The Z2 also can hook into the speed sensor wire for navigation without satellite.
The Alpine W505 is also worth a look, but I really didn't like the menu and interface. But the screen on it is MUCH higher resolution than most decks.
http://avic411.com was very helpful in my research.