Hi,
I have this 7" TFT (5 Inches HDMI Capacitive Touch Screen (Driver free) for Pi, BB Black, PC, Mac Book - Free shipping - DealExtreme) and works fine in Arduino, except because the image show mirrored (probably is a problem with the graphic libray: uTFT).
The display has a touch pannel, and a SD card reader.
Use 20 pins of Arduino (and 2 for the power, of course), so you can use the Arduino MEGA without problems...
Regards,