The United Kingdom’s National Archives provides a great World War I history resource with their site “The First World War: Sources for History.” It provides a look at WWI from a British standpoint, enabling visitors to further understand Britain’s involvement in the conflict. The Web site is made up of dozens of options, including exploring service records from the war, a comprehensive explanation of all the battles and the aftermath of WWI.
Actually, it is almost too much information. It is a bit difficult to navigate and there is no “search” option (although there is a site map.) Nevertheless, it is a good Web site that one can explore if one is just looking to learn more about the conflict, particularly Britain’s take and involvement.
History on the Web 
Readers will also enjoy Soldier’s Mail: Letters Home from a New England Soldier 1916-1919 which features the writings of U.S. Sgt. Sam Avery during the American involvement in the Great War. A compelling eyewitness narrative from the hot sands along the Rio Grande to the cold mud along the Meuse.
http://worldwar1letters.wordpress.com