The NSA's Cryptolog
The NSA has published declassified versions of its Cryptolog newsletter. All the issues from Aug 1974 through Summer 1997 are on the web, although there are some pretty heavy redactions in places. (Here’s a link to the documents on a non-government site, in case they disappear.)
I haven’t even begun to go through these yet. If you find anything good, please post it in comments.