• A Mollier Diagram, provided with the DOE Fundamentals Handbook, adapted for web use.
• Steam Tables published by faculty from Harvard and MIT.
• The Generic Fundamentals (GFES) Formula Sheet.
• A zoomable Chart of the Nuclides.
• The DOE Fundamentals Handbooks, (formerly known as the Reactor Operator Fundamentals Manuals)
• Generic Tech Specs, published by the NRC

I've also included a link to a new wiki site, that I intend to work on in the future.

As far as I know, NRCprep is the only site on the internet that provides FREE access to Steam Tables and Mollier Diagram.  I hope many others in the nuclear industry will find these resources helpful.