Here are some new resources that I'll be adding to the Libraries' Communication Arts & Sciences page (link to change soon)...

Castro Speech Database
Fidel Castro's Speeches, 1959-1996

Selected Speeches of Winston Churchill
Courtesy of the Churchill Centre & Societies

Kennedy Speeches (JFK, RFK and Teddy)

American Leaders Speak: Recordings from World War I and the 1920 Election
Taken from The Library of Congress' site description: The Nation's Forum Collection consists of fifty-nine sound recordings of speeches by American leaders from 1918-1920. The speeches focus on issues and events surrounding the First World War and the subsequent presidential election of 1920. Speakers include: Warren G. Harding, James Cox, Calvin Coolidge, Franklin D. Roosevelt, Samuel Gompers, Henry Cabot Lodge, and John J. Pershing. Speeches range from one to five minutes.