I'd say it is all a matter of preference. Since you mention CF I assume that you have Centrafuse installed, this comes with gps software(europe only), obdII interface, Dvd and music player, XM TV and radio if you have the required hardware, And phoco for interfacing with a bluetooth enabled phone. All these should give you a good base for whatever you want to do in a car.
Since you mentioned snes9x I would suggest mobile emulator which includes snes9x along with a few other emulators and makes it easy to use an emulator in your car through a touch screen for at least selecting the game.
Other then that its up to you, if you have a different gps software you prefer use that instead. Mostly just think of what you would like and search, if its a program that hasnt been made yet and you dont know how to program you can ask, not guaranteeing that you will get a good response or have it the next day or week if you do but people are willing to help.