I just put in a Harman Kardon TrafficPro, which I love. It is a 35 watt RMS radio and CD player that fits in the normal DIN slot and has full GPS navigation with voice prompts. It uses gyroscopes and input from the speedometer to combine inertial navigation with GPS updating to give a quicker response and also to allow it to function in cities and other places signals can get blocked. Looks perfect in the 911 dash, too.
http://hktrafficpro.com/