NIST Chemistry WebBook
Provides thermochemical, thermophysical, and ion energetics data compiled by NIST. This site allows users to search for data by chemical formula, chemical name and CAS registry number.
MatWeb (Material Property Data)
Includes data sheets of thermoplastic and thermoset polymers such as ABS, nylon, polycarbonate, polyester, polyethylene and polypropylene; metals such as aluminum, cobalt, copper, lead, magnesium, nickel, steel, superalloys, titanium and zinc alloys; ceramics; plus semiconductors, fibers, and other engineering materials.