• Calendar Zone   
  
  Comprehensive categorized calendar catalog currently containing countless correlating connections and calzone recipes.
  http://www.calendarzone.com/

• Calendars and Their History
  
  Discussion of the history of calendars and their reform.
  http://astro.nmsu.edu/~lhuber/leaphist.html
• Calendar Converter
  
  Hebrew, Gregorian, Islamic, Mayan, and many other calendars available for conversion.
  http://www.fourmilab.ch/documents/calendar/
• Calendar Date.com
  
  Find the calendar day that any two same month-dates occur on for different years or use the Date Calculator will figure the number of days within a time period specified.
  http://www.calendardate.com/
• Calendar FAQ
  
  An overview of the Christian, Hebrew, Persian, and Islamic calendars in common use. It will provide a historical background for the Christian calendar, plus an overview of the French Revolutionary calendar, the Maya calendar, and the Chinese calendar.
  http://www.tondering.dk/claus/cal/calendar27.html
• Calendar Studies
  
  Discusses various calendars, accuracy and reform.
  http://www.hermetic.ch/cal_stud.htm
• Coptic Calendar
  
  The Coptic calendar has its origin in the calendar of the Ptolemaios IIIrd Euergetes Ist. The calendar is still used today in the Coptic church.
  http://www.kalendersysteme.de/english/calendar/systems/ calendar_11.html
• Doomsday Algorithm for the Day of Week
  
  The Doomsday algorithm gives you the day of the week for any date (and you can do it in your head).
  http://www.cst.cmich.edu/users/graha1sw/pub/doomsday/ doomsdayintro.html
• Ecclesiastical Calendar
  
  Calculation of the Ecclesiastical Calendar.
  http://www.smart.net/~mmontes/ec-cal.html
• English Calendar
  
  This site is intended to replace handbooks of dates for students of English history and literature.
  http://www.albion.edu/english/calendar/
• Hijri Dates Converter (Islamic Calendar)
  
  Convert from Gregorian to Hijri or Hijri to Gregorian.
  http://www.rabiah.com/convert/
• Hindu Calendar
  
  http://www.hindunet.org/hindu_calendar/
• Java Perpetual Calendar
  
  Your basic calendar. Enter the year and month and it will return that month's calendar.
  http://my.execpc.com/~mikeber/calendar.html
• Literary Calendar
  
  An almanac of literary information and events.
  http://english.yasuda-u.ac.jp/lc/
• Maya Calendar Tools
  
  Calendar conversions regarding Maya calendar.
  http://www.pauahtun.org/tools.html
• Mayan Date Calculator
  
  http://www.halfmoon.org/date.html
• Roman Calendar
  
  http://www.personal.psu.edu/users/w/x/wxk116/ RomanCalendar/
• Roman Calendars from Romulus to Julius Caesar
  
  http://www.12x30.net/earlyrom.html
• Solar Lunar Calendar (Chinese Calendar)
  
  http://umunhum.stanford.edu/~lee/chicomp/lunar.html
• Today's Calendar and Clock Page
  
  Automatically delivers today's date in calendars of all sorts follwed by various calendar links.
  http://www.ecben.net/calendar.shtml
• Virtual Perpetual Calendars
  
  Contains calendars such as the Julian, Zodiac, seasons and more.
  http://www.vpcalendar.net/
• Zoroastrian Religious Calendar (Fasli)
  
  http://www.avesta.org/zcal.html

     See also, these cross-references:

• Almanacs and Facts
  
• Encyclopedias
  
• Horoscopes & Astrology
  
• Today in History