This bad boy of a gadget projects an image from a retrofitted camera at the exact moment another camera snaps a picture with flash. This creates an invisible illusion to the human eye only seen after the picture is taken. This is the brain child of Julius von Bismarck from Germany. In a recent interview from Wired.com he stated that this is the first prototype with many others in the works. Fearing large corporations trying to steal his idea for marketing purposes he refuses to publicly disclose them.
Its a very simple idea done right. This is a great way to stealthily sneak your own messages or images onto highly photographed events, locations, people, etc. I can see how viral marketing companies would like to invest on this for their own evil purposes. So next time you snap a picture, make sure there are no hidden URLs or messages on your picture.
http://www.juliusvonbismarck.com/fulgurator/index.html
http://www.wired.com/gadgetlab/2008/06/exclusive-inter/