I see that you got a point there Dev. But the tempatetion for gadgets... simply too much.
On the other hand if you have an on board computer the possibilities are endless:
* Audio support to virtually a limitless set of codecs: Divx, MP3, WMV, etc.
* Add on GPS (when the usage is legalized)
* DVD, DVDR, DVD RW support
* Mobile internet
* Bluetooth pairing with phone
* Hooked up with proper sensors for car security
* Forward/Aft parking support by sensor/camera
* Hooked up with OBD for real time monitoring
* ETC. you think about it, it could be done