As a way of demonstrating the profound inequality that exists in our world, Google has put together a powerful site.
Google's gapminder shows one- and two-variable plots of international data. Want to know the international distribution of across nations? No problem. Want to know how life expectancy varies by nations' wealth? There it is. Want to know how life expectancy has changed over time for a specific country? Easy. For a 1 minute tutorial.
(Thanks to Jay Livingston)