A Canadian company Mirage Motion Media came up with a technology that creates an illusion of motion for static billboards. Business Week is ebullient: "Mirage Motion Media has a new billboard technology that, even in our image-saturated world, is about to confound us all -- and perhaps reinvent outdoor advertising in the process. Mirage's "interactive motion panels" play "video" clips -- albeit without the use of any electronics or moving parts -- on seemingly standard advertising light boxes. Walk by, and the picture moves. Stop, and it stops with you. Like a fun-house mirror, it begs passersby to do a little jig in front of it to see what will happen."
More on how these things work at Billboardom.