Chemical Heritage Foundation

Site devoted to the history of chemistry. One can find biographies of chemists, information on exhibits and activities and much more.

ChemSpider

A chemistry search engine "built with the intention of aggregating and indexing chemical structures and their associated information into a single searchable repository"  Includes inherent properties, identifiers and references, links to wikipedia, associated data sources and commerical suppliers, patent information, PubMed articles, supplemental information, etc. 

"Google" Patent Search

International Union of Pure and Applied Chemistry

"Serves to enhance the worldwide aspects of the chemical sciences and to contribute to the application of chemistry in the service of mankind. The IUPAC is recognized as the world authority on chemical nomenclature, terminology, standardized methods for measurement, atomic weights and many other critically evaluated data."

Links for Chemists

This site has links to all kinds of information: university chemistry departments, organizations, industry, literature, chemical information, and other topics.

PubChem

Use this site to find information on the biological activites of small molecules. Searching can be done by compound, substance, bioassy, and structure.

United States Patent and Trademark Office

Searchable for issued patents and published applications. Patents are full text since 1976. Full page images go back to 1790. Patents from 1790-1975 are searchable only by patent number and current US classification.

WWW Chemistry Resources

Similar in content to the "Links for Chemists" site above. This site has not been updated recently.