The permanent collection of the (US) National Veterans Art Museum in Chicago contains more than 2,500 pieces of art by 250 artists, all of which can be seen at NVAM Collection Online. The site includes biographical material on the artists who created the work. Featured Artwork. A small selection. (Via. Images at links in this post may be nsfw, and/or disturbing to some viewers.)
Speaking of Veterans Day, here in Chicago we have the National Vietnam Veterans Art Museum. Art by Vets about the War. Most pieces are on-line with a short essay. The Above and Beyond memorial is impressive to say the least.