Just really cool, and yet with a wealth of deeper levels to plumb, this visual map of per capita income and life expectancy for the world's nations (dynamically shown from 1975 until today) blew my mind. I think I've run it a dozen timea already, following different questions/aspects on each pass.
(via coworker LRP)
Update: a grim observation here -- you can watch the effect of AIDS in Africa by tracking the plummet in life expectancy during the 80s and 90s. eep.