Secondly, St. John wasn't referring to the Devil, but using Hebrew gematria to refer to Nero (the article is a good summary of various "end-times" theories, including the Catholic approach) in a coded note to persecuted Christians. So unless you're time-travelling to Imperial Rome, I wouldn't be more concerned about demonic activity today than you were yesterday. "666" is mostly something for teens to have tatooed on themselves to freak you out.
On the other hand, I apparently do live in the City of Satan:
to the trained eye, the upside-down star, apparently known as the Devil's Goathead of Mendes, "one of the most important types of the five-pointed Devil's Pentagram," is right there staring at us, we are told. "There is 666 evident in the most important top three circles of the Goathead -- Dupont Circle, Scott Circle, and Logan Circle. Each of these streets has six major streets coming into them from all angles of the circle. This type of encoding is so typical of the occultist." Most important, however, the "Southernmost point, the spiritual point, is precisely centered on the White House. . . . The meaning is all too clear."
Goathead of . . .Mendes? No wonder Bush the Great Satan is soft on immigration!