Conceptual Diagram Symbol Libraries

Conceptual Diagram Symbol Libraries, at the Integration and application network offrers the IAN symbol libraries, containing over 1500 custom made vector symbols (in 32 categories) designed specifically for enhancing science communication skills. The libraries are designed primarily for use with Adobe Illustrator (requires version 10 or better), however they also offer eps and svg versions for non-Illustrator users. The symbols allow diagrammatic representations of complex processes to be developed easily with minimal graphical skills. The libraries are provided completely cost and royalty free.
Very useful, especially for environment and earth science related illustrations and concepts. The site contains detailed explanations of the contents of the library, suggestion uses and tutorials.