World flight path map: Busiest airports are Atlanta, Frankfurt, Sao Paolo, Beijing.
Rohit Khare stashed this in TRAVELMAN
Perhaps the most fascinating thing about the map is that there's no "base layer" tracing the outlines of countries or continents. Instead, the flight routes themselves sketch the edges of the world's major land masses, because so many people live in and travel between coastal cities.
Seriously, truly fascinating.
Also, Atlanta being the busiest is a surprise. I would have guessed Chicago O'Hare or Dallas-Ft. Worth.