[quantumet]

I think Claude Shannon's (of information theory fame) master's thesis beats out all others in the field of computer science.

"A Symbolic Analysis of Relay and Switching Circuits", 1938, proves that you can use electrical switches to do boolean algebra! He basically invented the digital computer, as a master's thesis.

[sp332]

Not to diminish Shannon's genius at all, but he wasn't the first to make logic circuits. http://projecteuclid.org/DPubS/Repository/1.0/Disseminate?vi... On page 917 you can see Charles Sanders Pierce and Alan Marquand made some in the 1880's.