+Chemistry Resources: Free (and often overlooked) Chemistry Resources

The Web Book provides chemical and physical properties data for atoms, molecules, ions, and other chemical species.

This open access database maintained by the National Institutes of Health contains information on "chemical structures, identifiers, chemical and physical properties, biological activities, patents, health, safety, toxicity data, and many others."

Database compiled by the National Institute of Advanced Industrial Science and Technology in Japan. IR, NMR, MS, Raman, and ESR spectra are available. Users may also input spectral data to determine an unknown substance.

The Chemical Education Digital Library (ChemEd DL) is a gathering place for resources and communities for those in the business of teaching or learning chemistry.

Database maintained by the Pesticide Action Network (PAN) of North America. It is searchable by chemicals, products, poisoning diagnostic information, and chemicals responsible for aquatic toxicity.