He has been credited with nothing less than keeping the publishing industry afloat, but that's just the start. In March 2003, Dan Brown, 40, published his fourth novel, The Da Vinci Code, a historical thriller purporting to expose a centuriesold Vatican conspiracy to conceal the marriage and offspring of Jesus Christ and Mary Magdalene. Since then, the book has sold 25 million copies in 44 languages worldwide, and Brown has been held responsible for renewed interest in Leonardo da Vinci, Gnostic texts and early Christian history; spiking tourism to Paris, Rome and a 15th century church outside Edinburgh, Scotland; a growing membership in secret societies; the ire of Cardinals in Rome; eight books denying the claims of the novel and seven guides to read along with it; a flood of historical thrillers; a movie starring Tom Hanks; and an NBC reality show, now in development, in which contestants will use history and folklore to solve arcane puzzles. Pretty impressive, given that the New Hampshire native's three previous works barely caused a ripple and, strictly speaking, the novel is heretical. It's perhaps worth noting that one of the very few books to sell more copies than The Da Vinci Code in the past two years is the Bible.