The Image Fulgurator is a projector disguised as a camera. When it detects a flash from a real camera, it projects an image onto its target for an instant. The fleeting projection might not be noticeable to the naked eye, but it appears in the picture that was taken at that moment. It won the 2008 Golden Nica, and was created by Juilius Von Bismarck, who has an awesome name.
Here’s a video documentary about the device. It’s a long, languid video, but it’s good, and there’s a clear demonstration of the Fulgurator at the 12:30 mark.