Two relatively similar tips recently arrived in the infosthetics suggestion box.
Anna points to a small movie [.wmv, radar.zhaw.ch] created by Swiss air traffic engineers that shows all the flights within a timespan of 24 hours. Each airplane is represented as a moving yellow dot on a world map. One can clearly perceive the changing dynamics from daytime to nighttime.
Mario points to Air Lines [lx97.com], an art project showing worldwide airliner routes on a world map. Every single scheduled flight on any given day is represented by a fine line from its point of origin to its port of destination. As a result, a net is formed out of thousands of lines. Hubs like JFK, FRA or DXB turn into dark knots where lines meet, lesser served local services are only are a subtle hint. The maps is also commercially available as a poster.