Passwords (for computers, ATM machines, etc.) might be made much more effective if, in addition to denying access to those who type in the wrong password too many times, they were supplemented with a flock of "pseudopasswords": strings which look just like a legitimate password, but which when used by the - presumably unauthorized - user, track and possibly ensnare her! This should be a no-brainer for any security expert, and I can't believe it isn't already part of some encryption schemes. It should be easy to implement by any half-decent system manager, and presumably would increase security by the Nth-power of the existing security, where N is the number of pseudopasswords each account has....