National Security Agency
Official NSA site. Coordinates, directs, and performs highly specialized activities to protect U.S. information systems and produce foreign intelligence information.
Remarks By General Michael V. Hayden
Text of a January 2006 speech to the National Press Club by General Michael Hayden, former director of the NSA.
Wikipedia: National Security Agency
Article about the NSA, the ultra-secretive spy agency that is responsible for the collection and analysis of foreign communications and for the security of US government communications against similar agencies elsewhere.