Building Symbols, Hospital Symbols, Railway Symbols, etc
These are free to use symbols designed for use in the different environments. These are available courtesy of this website.
These free to use symbols designed for use in the Airport environment, that are available courtesy American Institute for Graphic Arts (AIGA).
This contains more than 2,500 Western signs, arranged into 54 groups according to their graphic characteristics. In 1,600 articles their histories, uses, and meanings are thoroughly discussed
Links to traffic sign and symbols
Manual of Traffic Signs
This is a listing of the most commonly used traffic signs in the United States.
Collection of peace signs from all over the world
A collection of funny signs
Symbol Signs for HCI
Related to Symbol/Signs for Human-Computer Interaction
International Signs Online
Links to the art, law, history and humor of signs around the world