Touch screens are everywhere these days. The Maker Shed has a TouchShield Stealth for use with the Arduino environment. Now that the Arduino Mega has been released the bigger TouchShield Slide is also available. Liquidware Antipasto posted some great code to help you get started with your own touch screen project:
I’m making the TouchShield tell the Arduino to turn on an LED. The Arduino code is compatible on the Duemilanove and the Mega. The TouchShield code is compatible on the Stealth and the Slide.
More about the Arduino Mega in the Maker Shed