I want to hold up various elements from my Ikea box, have a gesture-reading device like Kinect see it, and have the TV walk me through interactive instructions on how to put together my new bed. Don't know what this random piece is or where it goes? Hold it up, and a rotate-able 3D schematic shows me exactly where it fits into the finished bed, with a link to the step where that piece is used.
First thing one would do is start a little venture that would transcribe the entire Ikea PDF catalogue into interactive 3D models. Who's in?