1.

PBS.org - World War I

2.

BBC News: World War I Remembered

3.

Eye Witnesses to History
(Includes the assassination of Archduke Ferninand in 1914)

4.

PBS.org - Timeline

5.

Women in World War I

6.

Posters of World War I

7.

Spartacus.schoolnet.co.uk
(Has index to information about important people and more.)

8.

WWI Biographical Dictionary

9.

Aircraft and Aces of WWI - The Aerodrome

10.

Experiencing War - WWI - Library of Congress

WWI and America's Involvement