I was talking to a friend of mine who works at the Technisches Museum Vienna the other day about Enigma and Colossus, since I had just heard Jack Copeland‘s talk at the Gödel Centennial about the history of Colossus. So I did some Googling and found some interesting books which I should get: Action This Day, edited by Michael Smith and Ralph Erskine (2001), about code breaking at Bletchley Park; and the new Colossus. The Secrets of Bletchley Park’s Code-breaking Computers, edited by Jack Copeland (2006).

Other things which Google spat out:

• A review of Action This Day from the CIA.
• Wikipedia entries on Tommy Flowers, who built Colossus; Tunny, the coding machine Colossus was used against; and an entry on the cryptanalysis of Enigma.
• An article on Colossus by Copeland.