An OverlapMap is a map of one part of the world that overlaps a different part of the world. OverlapMaps show relative size.
This is an very simple way to demonstrate the true size of places, and 'bring the discussion home.' This site is as simple and intuitive as it is powerful and easily applicable. This is a keeper.
Via Seth Dixon, Jarett Schiebel, dilaycock, Joanne Wegener