Most archival records held by NARA are available to the public for research and are either unclassified or declassified
Central Intelligence Agency (CIA) Freedom of Information Act (FOIA) Electronic Reading Room.
George Washington University. The world's largest non-governmental collection according to the LA Times.
Government Information Library - University Colorado, Boulder - extensive list by agency and department.
FBI's FOIA Library, containing 6,700 documents.
OpenNet database with 485,000 bibliographic references and 140,000 recently declassified documents.
National Security Agency released documents.
Intelligence and security service released files.