DisplayLink has an application for the iPad that lets you use your iPad as a second monitor on a Windows PC. Wha? Yep you can use your Apple iPad as a second monitor for a Windows product, specifically XP, Vista, and 7. No need to run cables, this magic is accomplished wirelessly.
I use two monitors on my work computer and can never go back to using just one screen. The productivity gains with two monitors is amazing. Now I can do the same thing on my laptop at home, slick. This has to be one of the best iPad apps to date,
Here is the iTunes link to the Displaylink iPad ap – http://itunes.apple.com/us/app/displaylink/id411678720?mt=8