When in-dash Car DVD players aren't enough for you, you should think about providing a full video / gaming / car pc upgrade for all the seats of your car. For the passenger in the front you can put in a sun visor monitor, and for the back there are headrest screens or roof monitors for bigger vehicles. A 15" roof monitor would normally be suitable for a bus, so in a normal car you'll have a truly impressive sight.
See also the Gigxon.com car video products for bringing your car's sound to life, and of course the main Car DVD players category for car in-dash video.Unless otherwise stated, all the Car video devices here will work in any country in the world. Make sure you get the choose the correct side for sun visor monitors though.