I bought a Nokia N82 display with an Arduino interface board from Andy Brown. I have mainly used it plot real-time wave forms, but not very seriously yet. I might use it as a display for leJOS on RPi. It seems the cheapest way to get a high-quality TFT display for an Arduino. It works best with the Arduno Mega, but can be used with an Arduino Uno if you have lots of suitable connecting wires.
The library that Andy has written is excellent.
Here it is connected to an Arduino Mega clone: