In my internet travels I stumbled on this site, The Literature of Intelligence, dedicated to nonfiction books and articles on the Intelligence business. I’ve only just begun to scratch the surface of what is found there but the depth of information collected is pretty extraordinary. Being organized by a former member of the CIA turned university professor, it also has a pretty good pedigree.
If there is an particular aspect of the history of spies you are interested in, this bibliography has a laundry list of books and articles relating to that area. For anyone interested in some type of scholarly exploration of the intelligence world, this is the place to go.
Even if you’re not interested in the bibliography itself, I recommend checking out the definition of Intelligence. It’s a refreshing look how countries view the reality of the business.
If there is one thing I would change, it’s the very basic web design, circa 1999, but a pretty website isn’t essential for this type of information. If you like true spy stories, this is the place to find some new material.