The the Presidential Recordings Program at the University of Virginia’s Miller Center of Public Affairs has made available an archive of White House tapes. You can listen to more than 5,000 hours of White House conversations recorded between 1940 and 1973 by six American presidents:
Transcripts are also available for selected tapes from the Kennedy administration. There are also some interesting virtual exhibits featuring the tapes. Topics include civil rights, Vietnam, the space race, and politics.