(Via Survival Blog)
Circulating around the Intertubz (I saw it on SurvialBlog first, followed in rapid succession on 2 email lists and Facebook, for Pete's sake) is this very entertaining and interesting map that gives some insights into the flow of population around the US.
I'd really like to see one for flows into and out of the US to other countries. Of course, that one might scare good old John Q. Public right out of that Laz-e-boy and make him spill his beer, so I doubt that happens.