FBI's Electronic Reading Room - displaying frequently-requested documents released under the Freedom of Information Act, including documents related to espionage.
Central Intelligence Agency - official site that includes an overview of the agency and its mission. Also links to the World Factbook.
UK Government Communications Headquarters - Intelligence gathering agency that is charged with helping safeguard the nation's security, economic well-being and to protect it against serious crime.
The Complete, Unofficial TEMPEST Information Page - learn more about how with the right antenna and receiver, electromagnetic radiation from computer monitors and other devices can be remotely intercepted, redisplayed, recorded and replayed.
Cold War: Espionage - learn about spies and espionage techniques used during the Cold War. From CNN.
