General Reference: Date and Time Facts
A Walk Through Time
This excellent resource from the National Institute of Standards and Technology (NIST) includes information on ancient calendars, early clocks, world time scales, and a NIST time calibration. A modest bibliography of some twenty sources is also provided.
AnyDay in History
Selecting a date generates a list of important historical events which occured on that day.
Calculation of the Ecclesiastical Calendar
Inputing a date after A.D. 325 furnishes the user with information on the movable feasts associated with Easter for the year provided. Dates for both Julian and Gregorian calendars are included.
Today In History
Maintained by the Library of Congress, this site discusses at length one historic event which occured on today's date. A searchable archive is also available.