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/
There is an interesting
site dealing with the abacus:
http://www.ee.ryerson.ca/~elf/abacus/