NUKEMAP!
I seem to be obsessed with apocalyptic google maps at present. Soon after finding The Map of the Dead, another cool map comes along. Nukemap. It is morbid but kind of fun. Basically, you set a point on google maps, select a bomb size (from existing nuclear arsenals), then hit detonate. The map then shows things like the initial blast zone, lethal radiation zone, and so forth. You can even programme the kiloton yield yourself.
We are thinking about a house, so obviously it is prudent to see how far away from the centre of London we should live in case a terrorist blows up Parliament with a dirty bomb. (I think having just typed that last sentence my readership at MI5 just went up.) As I said, it’s a bit morbid but it is interesting. The Nukemap is here.