Wikipedia: Maya Calendar
Encyclopedia article about the complex calendars developed by the Maya Civilization of pre-Columbian Mesoamerica, which include a sacred 260-day calendar called the Tzolkin, a 365-day calendar called the Haab, and a 52-Haab cycle called the Calendar Round, which synchronised the Tzolkin and Haab cycles.
Wikipedia: Mesoamerican Long Count Calendar
User-created page dedicated to the Mesoamerican Long Count Calendar. Features seemingly authoratative mathematical and scientific data and numerous embedded links.
13-Moon Natural Time Calendar
The 13-Moon Natural Time Calendar uses the mathematics of the ancient Mayan Calendar to shift our everyday consciousness and live in harmony with galactic time. Site includes interviews with and writings by Dr. Jose Arguelles, and interpretations of Mayan prophecies.
Mayan Calendar Calculator
Online tool for converting between Mayan and Gregorian calendar dates, with background information about the Mayan calendar.
The Maya Calendar
Information about the Mayan calendar, with Maya and European dates, the correlation problem, and the yearbearer systems. In English, Spanish, and German. By Peter Meyer.