The following is a collection of links to other terrific engineering sites containing more software and general information:

About.com: A great site that not only has extensive Chemistry and Chemical Engineering sections, but sections on just "about" anything of interest.

ASMENET: Web site for ASME (The American Society of Mechanical Engineers).  This site has perhaps the world's largest collection of Engineering software (all disciplines) available. 

ChemIndustry.com: THE search engine for the chemical industry.

Engineering Power Tools:  Here is a shareware library of over 70 engineering programs that can be used to quickly solve a wide range of commonly encountered engineering problems.

LMNO Engineering, Research, and Software, Ltd.:  A high quality site featuring interactive calculations on fluid flow, hydrology, hydraulics, flow measurement, and unit conversions.

NIST: The National Institute of Standards and Techology.  This is a US government organization established by Congress to assist industry in the development of technology.  Compare the data generated by PhysProps with that from the NIST Chemistry WebBook!