The Bomb Site Project

During 1940 and 1941 London suffered from the Blitz, when Nazi Germany mounted an aerial bombing campaign against civilian as well as military targets. Being Britain, the bombed sites were all marked on maps, which are now kept in the National Archives. However, thanks to the University of Portsmouth, you can visit the Bomb Sight project website and explore the maps online. It's been popular, very popular, peaking at six visitors a second, and is interesting for more than just Londoners checking if anything hit their locations. Marvellously, there's an Android function that lets you put the map over the top of the modern world (although I haven't used it.)