iPad as an Interactive White Board for $5 or $10

This setup is actually better than an Interactive White Board in several ways. Not only is it vastly cheaper, but it also permits a teacher or student to be anywhere in the room when writing on the iPad/projected computer image AND see the digital image on the device in their hands.

http://www.speedofcreativity.org/2011/03/24/ipad-as-an-interactive-white-board-for-5-or-10/