Ok, technically it's not the site that's cool, it's the program you can download from the site. An interactive program which gives you access to 3-D satellite images (which you can zoom-in to the point that you can see houses and buildings) of the planet with all kind of nifty customizable features and info.
Right now I'm looking at Saint Peter's Basilica from an elevation of 195 ft.
Schlesinger and the Decline of Liberalism
2 hours ago