Recently I have been playing with point tracking and object recognition in images. A natural thing to look at will be Augmented Reality and all the stuff being done with overlaying 3d renders on video. I got a nice toolkit called BuildAR and played around with some hand drawn targets being tracked.
As a more complex demo I would like to build a tracked sculpting surface which lets you carve or shape a virtual blob with real world hand movements and 3d dexterity. Very similar to the 3d graffiti shown here.
2 more cheap webcams are on the way so I can pretty easily do a 3d setup like in the video for sculpting on a table. The same setup can be used for vision based control system for the quad using OpenCV Posit.