The Dave Rumsey site has a cool Web based 3D GIS viewer with historic maps like the Lewis and Clark Expedition and an 1880’s map of Los Angeles basin. The maps can also be viewed on Google Earth viewer. They provide a video of the 3D process. E-perimetron has an article on “3D digitization of historical maps”. E-perimetron is the the international quarterly e-journal on sciences and technologies affined to history of cartography and maps.