oclHashcat-plus is a "password-recovery" tool that chews through 8-million guesses a second. It optimizes its guesses by trying phrases from "the Bible, common literature, and in online discussions,” and by formulating characters into websites' required "password-construction protocols."
One security researcher cracked the passphrase “Ph’nglui mglw’nafh Cthulhu R’lyeh wgah’nagl fhtagn1,” a phrase from an H.P. Lovecraft horror story. It was less impossible than it was super easy, crackable in minutes, because it was in an easily available hacker word list.