This is one of the best all around sites that I have found. It is titled “The MacTutor History of Mathematics Archive.”

http://www-history.mcs.st-and.ac.uk/~history/

This is an award-winning site that links to all sorts of mathematics information.

http://archives.math.utk.edu/

**These sites are dictionaries of units of measurement. This site has many nice links to other sites.**

http://www.unc.edu/~rowlett/units/index.html