I'm sitting in the opening session at Where 2.0 still marveling over the mapping mash-ups done by David Rumsey. He's a collector of historic cartography with over 11,000 different maps available from his site. On stage Mr. Rumsey demonstrated some killer combinations of 3D topographical maps overlayed with some of the historic maps in his collection. While this seems gimmicky on the surface, it actually makes flat mapping more relevant because the maps are integrated in context with the environment. One timely example is a Rumsey archive map from the Lewis and Clark expedition paired with a 3D topographical view of the same path covered by the expedition. Sure you could re-create a similar map using software, but to get the perspective of historically hand drawn map from a 30,000 foot view of the topography, integrated with the ability to zoom in on specific locations and follow the Lewis and Clark trail, a new perspective is created. I'm not describing this with the same effect viewing the maps onscreen made, but it's seriously one of the most unique mapping tools I've seen.