Mapping Wikipedia is a Google Maps mash up that identifies the location of Wikipedia entries based on the geo-location data found on the wiki entry.
As a former geography teacher, I can think of several ways to explore our world with this kind of data mining. But as a web technology teacher, I find that the site shows just how polarized web content can be. Clearly the majority of wiki entries in English are about places in Europe and the United States. Language still divides us as it has ever since the Tower of Babel.