Reflection ($15.00) allows you to mirror your ipad or iphone to your computer.
Projecting from iPad
The other benefit of Reflection is untethered projection. This will allow you to use apps like Screenchomp, Showme, or Educreations as an interactive whiteboard. It is not as robust as an Apple TV but the price of an iPad and the fifteeen dollars for Reflection you can have an IWB for thousands less than the major brands.