Back during the d20 Boom, Larry Elmore released a book and CD-ROM of images for gamers to use. Some of them were licensed for reuse in a publishing project.
Teazia has been collecting public domain art for reuse (19th century/early 20th century fantasy images) and got Larry Elmore permission to post the images from the collection. You can browse and download the images from here. The last two images of the collection is a copy of the license and has more information on what you can and can't do with the images.