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

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

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

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

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/

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

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

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

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

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

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

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

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

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

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/

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/

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