The FogScreen is the advertising industry's latest weapon in the fight against peace and quiet. The projector can fill spaces like subway tunnels with floating ads that you can actually walk through. It sprays a very fine mist of dry fog, created from water by an ultrasonic wave, which can then be projected on to just as if it were a hard surface.
It's available in two models; the 79" Inia and the 39" One, but bigger images can be achieved by stitching more than one unit together. I'm guessing that it will take a while before people can strut through a full-size floating SUV without flinching though. [Sci-Fi Tech]