Check out 4DPi-35 Primary Display for Raspberry Pi – model A, B and B+. It plugs directly on top and displays the primary output as it normally sent out to the HDMI or Composite output. Features integrated resistive touch panel so you can operate Raspberry Pi without mouse!
This display is designed to work with Raspbian operating system on Raspberry Pi. It has high speed 48Mhz SPI connection with on-board processor. The display features a breakout header which enables all of the Raspberry Pi GPIO pins to be accessed while the 4DPi-35 in connected.
Buy 3.5” Primary Display for Raspberry Pi from Pakronics: