A Brief History of Time - Early origins and historical perspectives of time measurement.

The Calendar - Summarizes the history of various calendars developed and used over the centuries.

Calendar Studies - Information about calendar history and calendar reform.

Calendar Zone - A categorized collection of calendar related sites.

English Calendar - Includes an ecclesiastical calendar and a section on old and new style dating.

A Few Facts Concerning GMT, UT, and the RGO - Explains the differences between several time systems.

A History of Time - Explains the importance of concept of time in the history of mathematics, science and measurement.

Infoplease: Daylight Saving Time - Information and history about Daylight Saving Time all over the world.

International Standard Date and Time Notation - An overview of the ISO 8601 notation for dates.

Internet Encyclopedia of Philosophy: Time - Time has been studied for thousands of years. Nevertheless, many issues remain to be resolved. This article explores both what is now known about time and what is controversial and unresolved.

NIST Time and Frequency Division - The National Institute of Standards and Technology maintains time and frequency standards for the United States.

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" Author David Prerau talks about the complicated politics and curious history of DST, and he shares an excerpt from his book. [4:54 streaming audio broadcast]

This Day In History - Today in history every day - often with pictures and sound.

Time - Provides descriptions of several standards of time.

Time FAQ - Frequently Asked Questions about time (from sci.astro news group)

Time Zone and Daylight Saving Time Data - A directory of sites providing descriptions of civil timekeeping concepts, source code, databases, and maps.

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.

United States Code - Weights, measures and standard time.

U.S. Time Zones - History of standard time in the U.S.

A Walk Through Time - Evolution of timekeeping through the centuries.

Wikipedia: Time - Time is a common term for the experience of duration, and a fundamental quantity of measuring systems. Article explains time definitions, history of measurements, perceptions in religion, philosophy and science.

Z-Time - Article on the time at 0 degrees longitude. Covers the timezone origin, GMT, UTC, GCT, ZULU and JIG.