[ http://www.cardfarm.com/ ]
Custom e-cards for different holidays. Some cards are interactive and feature all the main periods including Valentines and Christmas.
History of the Holidays
[ http://www.history.com/genericContent.do?id=53343 ]
Site that provides information on the history of many widely celebrated holiday and how they came about.
Holidays for the Classroom
[ http://www.kathimitchell.com/holidays.html ]
Provides a list of sites and resources for teachers to use during different seasonal holidays.