I was looking at new web sites and this one was recommended by the History Channel. Organized by war volunteers, this site has ten categories with links that offer primary documents on a wide variety of topics of World War I. Categories include Document by Year (pre-1914 to Post-1918), Diaries,The Medical Front and WWI Image Archive. For those interested in history of this time period or perhaps researching their family, check out this site for the international resources of those primary documents.
The World War I Document Archive