The Dynamap is a low-tech way of superimposing differnt logical and geographical networks over one another. As Gizmodo puts it:
…using interlaced images, manages to put three different maps of Manhattan — a street map, a subway map, and one showing landmarks and neighborhoods — all onto the same surface. Tilt it to one side and you see the street map, tilt it another way and you see the subway map, etc.
(Thanks, Kevin!)