“Worldmapper is a collection of world maps, where territories are re-sized on each map according to the subject of interest.” [via] See how the map of the world changes when you look not just at land area, but at other factors, such as population, GDP, import/export flows, or HIV infections. There are literally hundreds of map projections. This would make a cool demo for <a href=http://conferences.oreillynet.com/where2006/Where 2.0, I think..
If you like this kind of thing, also look at Hans Rosling’s amazing visualizations at gapminder.org.