"An Echo in My Heart"
This excellent site has a collection of over 550 letters between a Canadian soldier and his new wife. Unfortunately, the soldier was killed in action. His wife continued to write letters to him in a diary format, making for a heart-wrenching collection.
http://sites.google.com/site/echoinmyheartsite/home
http://sites.google.com/site/echoinmyheartsite/home