I am endlessly fascinated by maps- and I thought I would share one of my favorite online map collections. Worldmapper.org [1] has hundreds of Cartograms, which are basically maps whose territories are re-sized depending on the shown variable. Enough technical talk, here's an example:

It probably wouldn't take you more than two or three guesses to figure out what this map is measuring, but it's HIV prevalence. In 2003, 4 out of every 10 people in Swaziland (which is in Southern Africa) were HIV positive. Sure, 4 out of 10 people is a lot, but seeing a map of the problem is stunning.

Here is Fuel Usage. Not surprising, the US is a bloated mess in this area, but the map highlights the problem (although Japan is outrageously large as well, does anybody know why?) .

I could post twenty more of these maps, but you can check it out for yourself. The Web site is clean, ad-free, and has hundreds of maps. Be careful if you're at work; it's hard to stop once you get started.