Gapminder.org -- terrific world data visualizations
This is an amazing information visualization from Gapminder.org. It displays a scatterplot of nations' life expectancy versus income per capita, and plays the trend across years. Countries are circles, sized by their population size. (So it's a weighted scatterplot... a "bubbleplot".)
Open in new window -- Fertility vs. Income.
It's very powerful -- you can actually change the variables on each axis, the coloring scheme, etc. Fertility vs. Income shows the well-known linear relationship that higher income countries have lower fertility. However, by playing over time it becomes apparent that middle- and low-income countries have been decreasing their fertility rates over the past several decades -- the entire line downshifts.
Numerous other interesting effects can be seen. It's fascinating to watch Hans Rosling's 2006 TED presentation: Myths about the developing world, in which he runs through this and another visualization, pointing out many phenomena. It's impressive how much you can communicate with good data presentation.
If you don't want to watch the video, here is the other he presents, of income distribution across different world regions:
Apparently Google has acquired the Trendalyzer software (the animated bubbleplot) developed at Gapminder. I hope that means it's in good hands; they say they want to enhance it and make it freely available. (Where I work we appreciate what Marissa Mayer has to say, so I'll believe that blog post :))
I was reminded of this site from the SSS blog, but I've been meaning to write about it for a while.