Here is another idea off which someone might make their million. We are familiar with advertisements projected onto a screen. We probably are familiar with advertisements projected onto a translucent surface. Apart from these, a transient screen could be created -- say on a shopping mall floor -- through a puff of mist, suitably controlled to create a "screen" -- an image being projected onto it. It would surely work best with simple images, for example "J&B" or "VW". Apart from the surprise factor, an added advantage is that it is, in an important sense, an immaterial screen -- people will not stumble over it or bump their heads on it -- in fact they could walk straight through it -- so that dramatic effects may be obtained.