The first chapter of Howard Wainer’s book Picturing the Uncertain World, entitled “The Most Dangerous Equation”, is available from Princeton. (The equation in question is the fact that the standard deviation of the sampling distribution is the standard deviation of the population divided by the square root of sample size.
John Cook wrote sleeper theorems, theorems that one only comes to understand the importance of long after learning them; his list includes Bayes’ theorem and Jensen’s inequality.
In 1971, Laurence H. Tribe wrote an article in the Harvard Law Review, Trial by mathematics: precision and ritual in the legal process, on whether it was legitimate to use probability in trials.
Nate Silver gave a talk at Google.