The animation above shows all scheduled flights over a 24h period (based on 2008 data). Every day 93,000 flights are starting from approx. 9,000 airports. At any time there are between 8,000 and 13,000 airplanes in the air. This animation was produced to be shown on the high definition 3D-Globe "Orbitarium" in Technorama - The Swiss Science Center in collaboration with Institute of Applied Information Technology InIT, Zurich University of Applied Sciences, Winterthur.
Now, think a few years from now where most planes will have sensors in engines, flaps, landing gear and how much performance/maintenance data they will generate. Boeing 787s are expected to generate 1/2 terabyte of data a flight.
Think how much data will be streamed to and from these planes as more airlines offer wi-fi at 12mbps and better speeds (as ViaSat is delivering on some Jetblue flights)
Or how many page views will FlightAware get as more families and passengers track flights (below is image from their Live Flight Tracker)
and depressingly think how much more emissions will go towards global warming – half a pound of CO2 per passenger mile.