There are also a few 1 DIN radios that have a small screen that will accomodate a backup camera, along with a host of slide out screen ones ( more $$$ ) that can have NAV and play DVD and a backup camera.
It's all up to how much you want to spend ....

( search crutchfield.com & sonicelectronix.com )

this one is $449 and has all the features you need :
Jensen VM9414 7" In-Dash GPS Navigation w/DVD/CD/MP3/WMA Receiver

NOTE: you will need an antenna adapter and a wiring adapter to install ANY after market head unit.

BIG NOTE !!! Whatever you decide to do, make sure you do the capacitor mod, search for the sticky on this forum, even if you keep the OEM radio.