How a Computer saved the world - Article from the American Computer Science Association about the history of Colossus (and IBM's involvement in WWII). - http://www.acsa.net/a_computer_saved_the_world.htm
Take a Tour of Bletchley Park - Information and photos on the Colossus rebuild project at Bletchley Park. - http://www.lightstraw.co.uk/bletchley/tour.html
Bletchley Park Museum : Lorenz Cipher Machine - Descriptions of the Lorenz cipher machine and the Colossus computer built to crack the code. Information on the rebuild of a working Colossus. - http://www.codesandciphers.org.uk/lorenz/index.htm
Nationmaster Encyclopedia: Colossus computer - The purpose, origins, and design of the world's first programmable digital electronic computer. - http://www.nationmaster.com/encyclopedia/Colossus-computer