American Leaders Speak, 1918-19
http://lcweb2.loc.gov/ammem/nfhome.html
Sound recordings of major politicians, c. 1920.

The Marcus Garvey and Universal Negro Improvement Association Papers Project
http://www.sscnet.ucla.edu/mgpp/
Documents by and about the black nationalists leader and his movement, including the only known recordings of his voice.

USAF Museum WWI History Gallery
http://www.wpafb.af.mil/museum/history/ww1/ww1.htm
Photographs of pilots and airplanes.

World War I Document Archive
http://www.lib.byu.edu/~rdh/wwi/
Both official and personal documents, focusing on diplomatic and military events.

World War I-Trenches on the Web
http://www.worldwar1.com/ Extensive information on all belligerent nations.