NSA’s Declassification and Transparency section which includes some really interesting resources for anyone who’s interested in the history of cryptography and for GMs running spy games. Amongst the documents are the “Ask Zelda” columns which might make good handouts for a Laundry Files game. There’s also a collection of UFO related material (complete with heavy redaction using marker pens) that should work well for Conspiracy X or Delta Green campaigns. There’s declassified material relating to various incidents and operations that may be of interest for any espionage game.
Anyone wanting to make authentic looking handouts might want to take a look as there are lots of clues from styles of documents, how they were marked classified, how parts were redacted, fonts used, headers, footers, logos and much more. One thing that amused me was several documents have boxes in which the words “horizontal line” is included as text presumably instead of having an actual horizonal rule.