Cartogram

http://flowingdata.com/2011/01/10/our-changing-world-in-cartograms/

A cartogram is a map type that uses a country's area to represent a certain metric. The actual size of a country will increase as its value gets higher, or its size will decrease if its value gets lower. In general, these maps distort countrys and certain regions to reflect non-geographic information about them. Take for instance, the cartogram above that shows the richest countries in the world based on GDP.