University of Utah
University of Utah: Prime Numbers
A discussion of Eratosthenes' development of the system of prime numbers. Includes a Java program that demonstrates the sieve.
University of St. Andrews (UK)
University of St. Andrews: Mac Tutor History of Mathematics Archive
The University of St. Andrews, Scotland, presents hundreds of biographies of famous mathematicians, histories of math in various cultures, and interesting facts on the development of important math concepts. This is a huge reference....
Other
Ancient Greek Number Codes
Credited to the Cornell University Greek Epigraphy Project, the content on this page explains (and illustrates through a chart) the Greek use of Alpha characters for numbers.