The behavior thing is awesome (the navigation pattern route suggested by the author). I am willing to bet that, if it were possible, capturing and analyzing the navigation patterns on any given website would lead to better design and even capture some user data that could be extrapolated (eg, my mother tends to navigate web pages differently than my much younger brother).

In any case, I can't tell you how many times I've gotten those damn captchas wrong. Makes me feel like an idiot...