World War I

World War I on the Web HUGE resource for information about all aspects of World War I. Most resources are British or German.
The Great War Companion site to the PBS series. Includes photos, maps, interviews, and much more.
WW I Document Archive This international archive of primary documents from World War I has been assembled by volunteers of the World War I Military History List. Both official documents and personal diaries and memorials are included.
The Doughboy Center - American Expeditionary Forces in WWI.
The Clock These are reprints of articles that appeared in The Clock during World War I.
Aftermath: When the boys Came Home This site examines what happened after the war in Great Britain and how those who served or died were treated and remembered.
World War I Chronolgy with related articles and documents.
Passport to World War I has lots of information and links to many other sites as well.
The Sinking of the Lusitania

AVIATION

The Aerodrome lists aces and planes from World War I by nationality. Some photos and biographical information is included.
Flying Circle Graphics has some great information about some well-known and some little-known WWI airplanes. Ever hear of a submarine plane?
Over the Front contains sample articles, artwork, and photos from Over the Front magazine.
World War I Aces has information about the flying aces and short articles about some aviation firsts.
WWI Fighters has photos and specs of many WWI planes.

Personal Accounts & Diaries

Death of an Air Ace Eddie Rickenbacker describes the last mission of one of his fellow Army Air Corps pilots.
Robert Lindsay Mackay's First World War Diary This diary covers the time from 1915 through the end of the war as seen through the eyes of this Scottish soldier.
From the Diary of a U-Boat Commander, this article describes the sinking of a British cargo steamer in 1916.