The coolest thing I've seen in the last five minutes: http://earth.google.com/

Not sure if I'll ever use this for anything other than wasting time, but I could see this being useful for visualizing a driving route or finding restaurants/businesses in places I'm visiting.  The animation of the maps is very cool, and the “tilt” angles are even better.  The tilt is really what puts the icing on the cake to me.  Even though it's 2D data, the angled visualization makes a huge difference in following a route.