About.com: A History of the Olympics
Delves into the legend which spawned the history of the ancient Olympic games and contains sections dedicated to each of the modern Olympic games, starting in 1900, as well as interesting Olympic facts.
Brief History of the Olympic Games
Features a fairly lengthy history of the games, beginning in ancient times, through modern times, and including myths about the Olympics, the importance of them, and the internationalization of the games in modern times.
Has highlights and information on the London 2012 Olympics.
Internet home of the Olympic Movement, visitors are provided with event information, results, and organizational references.
Official US anti-doping agency site features information about themselves, what they do, and also provides tools for amateur athletes.