Use your ipad as a second monitor!

This is great for road warriors who are already carrying a laptop and an iPad.

Need a 2nd monitor that's light and easy? You can leverage your iPad as a 2nd monitor for your computer in Extended Desktop mode!

AirDisplay from Avatron.

http://www.avatron.com/apps/air-display/

Installs a tool on your PC/Mac, and an app on IOS.  Cost is $10. Works over WIFI. Pretty slick.