My first book cover - Introduction to Psychology, 12th Edition by Dennis Coon
Posting high-resolution photos on your web-site brings in the occassional request for permission to use the photos is some publication. I've had requests before from Israel Ministry of Agriculture to use camel shots from Broome in one of their publications, and Busselton Online (which doesn't seem to be online anymore :)) wanted to use one of my shots of the area on their website.
A couple of weeks ago I got a request from Cangage Learning to use of of my Antelope Canyon shots on the cover of one of their text books. The website page for the textbook is
online now, and my Canyon shot made it through the review process to make the cover. While not on the same scale as a Nat Geo cover, making the front cover of a book by a reputable publisher is a nice achievement.