Recently found out about Map/Guid, Menu, and Cancel buttons getting into a diagnostic screen...question I have is..what can be done in this area?

 

I hate to be Captian Obvious, but I think you've answered your own question.

The diagnostic menu is to do diagnostic/troubleshooting on the settings of the navi system including the number of satellites in range, screen adjustments/tests, microphone/speaker adjust/test, version, car info such as the yaw rate and tire calibrate options, and it even allows for a demo mode likely used by the dealer in the showroom. Its really designed to give the operator a view into the system and monitor how its working. Also note that there are additional features available in this mode if you have the SCS Connector attached.

Whats an SCS Connector you ask? Look in the trunk of your car. Near the Navi DVD ECU, you'll see a grey connector that is not connected to anything. If you bridge the two wires on that connector, you'll open another menu once you're in the diagnostic menu. Don't forget to press "return" after you've bridged the connector or else you won't get the menu!