Worldmapper is a collection of world maps, where territories are re-sized on each map according to the subject of interest.

The maps presented on this website are cartograms, otherwise known as density-equalising maps. The maps of the world you are used to seeing attempt to represent countries according to their land area. A cartogram re-sizes each country according to some other variable - for example population, GDP, total births etc. New maps will be added during 2006.

via The Presurfer

related items:
Diffusion-based method for producing density equalizing maps