AIGA - Symbol signs: "The complete set of 50 passenger/pedestrian symbols developed by AIGA is now available on the web, free of charge. Signs are available in EPS and GIF formats.
About the symbol signs
This system of 50 symbol signs was designed for use at the crossroads of modern life: in airports and other transportation hubs and at large international events. Produced through a collaboration between the AIGA and the U.S. Department of Transportation, they are an example of how public-minded designers can address a universal communication need.