I stumbled upon a website recently that I found extremely intriguing. It is an online or virtual museum of Cryptographic equipment over the years. The museum is based in the Netherlands and contains a large number of physical examples of crypto gear. These are accompanied by in depth explanations of history and use among other things. I have only had a short time so far to browse the site but there is much to see. Although the museum is just on the web, they have had exhibits or their collection displayed over the years for the public to see.
Not all crypto gear is radio related, of course, but I know there are many amateur radio enthusiasts who are interested in this sort of thing. I hope some of you find this site interesting.