Clockworks: From Sundials to the Atomic Second
Short articles about several different methods of timekeeping, from Britannica.com.

*Earth View
This site shows a "current" view of a topographically correct, but flat, Earth, with areas of night and day in their appropriate locations. Zooming as well as other variables are adjustable.

*Earth Viewer
An amazing Java-based site that not only shows current areas of light and darkness on the earth (in both map and globe formats), this site also provides animations of diurnal and seasonal changes.

How Time Works
Another great page from Marshall Brain, providing a brief overview of clocks, measuring time, time zones, and more. Be sure to read though the fun pull-out on the right side of the page!

Time Travel
Essays from Carl Sagan and Clifford Pickover along with activities and a glossary about time travel from NOVA.

Walk Through Time
A brief history of the measurement of time.