Placeopedia is a brilliantly-executed Google Maps-powered site which aims to create a map of all the articles in Wikipedia which correspond to a real-world location. The site is attractive and slick and adding a new place from Wikipedia is extremely easy: you just start typing the name of an article and Placeopedia autocompletes as you type—a functionality that should be built into Wikipedia (Greasemonkey, anyone?)—and then you click on the corresponding location on the map. There's also RSS and raw XML data for the 50 most recently-added places as well as KML files for Google Earth. My only gripe with Placeopedia is that you have to click on a link in a confirmation e-mail after every single place you add; perhaps a necessary evil, but it would be nice to be able to add, say, five at a time.