A Few Facts Concerning GMT, UT, and the RGO
   Explains the differences between several time systems.
   http://www.apparent-wind.com/gmt-explained.html

A Walk Through Time
   Evolution of timekeeping through the centuries.
   http://physics.nist.gov/GenInt/Time/time.html

Atomic Clock Time
   Displayed in a variety of useful formats. Site is a front-end to U.S. government atomic clocks.
   http://www.atomictime.net/

Calendar Studies
   Information about calendar history and calendar reform.
   http://www.hermetic.ch/cal_stud.htm

Calendar Zone
   A categorized collection of calendar related sites.
   http://www.calendarzone.com/

Date Algorithms
   Provides descriptions, proofs and computer programming implementation examples to convert dates to various calendar dates for Julian, Gregorian, and Rata Die calendars.
   http://vsg.cape.com/~pbaum/date/date0.htm

English Calendar
   Includes an ecclesiastical calendar and a section on old and new style dating.
   http://www.albion.edu/english/calendar/

Infoplease: Daylight Saving Time
   Information and history about Daylight Saving Time all over the world.
   http://www.infoplease.com/spot/daylight1.html

International Standard Date and Time Notation
   An overview of the ISO 8601 notation for dates.
   http://www.cl.cam.ac.uk/~mgk25/iso-time.html

NIST Time and Frequency Division
   The National Institute of Standards and Technology maintains time and frequency standards for the United States.
   http://tf.nist.gov/

NPR : 'Seize the Daylight': A History of Clock Chaos
   Benjamin Franklin first called for the government to tinker with clock hours in the 1780s. But it wasn't until World War I that the United States adopted daylight-saving time as a way to get more efficiency out of the day. "Seize the Daylight"
   http://www.npr.org/templates/story/story.php?storyId=4572036

The Calendar
   Summarizes the history of various calendars developed and used over the centuries.
   http://www.skeptics.com.au/journal/calendar.htm

This Day In History
   Today in history every day - often with pictures and sound.
   http://www.historychannel.com/today/

Time
   Provides descriptions of several standards of time.
   http://scienceworld.wolfram.com/astronomy/Time.html

Time FAQ
   Frequently Asked Questions about time (from sci.astro news group)
   http://www.faqs.org/faqs/astronomy/faq/part3/

Time References
   To set your watch or clock accurately using a time reference. Explains the various options for residents of North America.
   http://htexplained.com/watches/TimeRef/

Time Zone and Daylight Saving Time Data
   A directory of sites providing descriptions of civil timekeeping concepts, source code, databases, and maps.
   http://www.twinsun.com/tz/tz-link.htm

Today's Calendar and Clock Page
   Information on all things relating to calendars, dates, holidays, and time. Find today's date on several different cultural and religious calendars. Includes section on Celestial data, countdown clocks, and information on the dates past events.
   http://www.ecben.net/calendar.shtml

United States Code
   Weights, measures and standard time.
   http://tycho.usno.navy.mil/260.html