So far, the State Historical Society of Missouri's World War II digital collection includes photographs and letters from servicemen during the war. Over time, more manuscript materials will be added.
The entire collection can be viewed here.
Of particular note is the SHS's ongoing project to digitize our large "WWII Letters" collection (C0068). This collection is the result of a joint project of the Western Historical Manuscripts Collection and radio broadcaster Ted Malone. Malone, who grew up in Missouri and began his career at KMBC in Kansas City in 1929, spent 30 years hosting the show "Between the Bookends" on the CBS radio network. In 1945, Malone appealed to his listeners to send in letters that they had received from loved ones during the war. Over 4000 people from all over the United States responded, often sending in handwritten copies of the original letters along with cover letters addressed to Malone. These materials are now preserved at the State Historical Society of Missouri. Over time, the entire collection will be scanned and presented online.
A direct link to the letters can be found here.