University of St. Andrews (UK)
University of St. Andrews: Mayan Mathematics
After a historical introduction, this site from the University of St. Andrews provides information about the mathematics of the Maya Civilization and shows just how advanced they were.
Other
Mayan Math
A basic, illustrated description of the math system developed by the Mayans. Includes a paragraph comparing the Mayan system favorably with the Roman numeral system of the same time.