Matt Blaze has written a fascinating paper about "cracking" traditional physical locks with master keys. Not only is it a good tutorial on locksmithing technology (I find the terminology especially interesting), but it is an interesting cross-domain consideration of security, looking at physical security through the eyes of a computer security thinker (who else would describe breaking and entering as "rights amplification"?).

Then, to take the mixing of worlds further, Matt writes about the reactions he's received to the paper, with the classic debate of secrecy vs. publicity in the field of security vulnerabilities, but this time among traditional locksmiths.