I was reading a Cool Tools review of a company that puts any image on blinds, wallpaper, or flooring, and one of the comments led me to some fantastic illusions made using photo prints on the floor. More info on the bathroom floor and elevator from the Amazing Illusions blog.
UPDATE: Turns out the bathroom was for a Photoshop contest and so, is faux. I hope somebody makes it real though! (Thanks, Dean Putney!)