ACKNOWLEDGED.(Amazon.com book reviewer Francis McInerney)

The success of "The Da Vinci Code,"a new thriller by Dan Brown, isn't exactly a riddle wrapped in a mystery inside an enigma, but it certainly is astonishing, because novels by unheralded writers like Dan Brown almost never debut at the top of the Times best-seller list, as "The Da Vinci Code"did, a few weeks ago. The secret, it seems, was an advance-copy bombardment of booksellers, authors, and reviewers--ten thousand free books delivered to readers whose opinions supposedly matter enough to stimulate the traffic in editions that are not free.

A small testament to the wisdom of this approach can be found, embedded like one of Brown's esoteric clues, in the book's acknowledgments. There, among the names of curators, cryptologists, and academics, is the name Francis McInerney; McInerney, as Amazon enthusiasts may know, is one of the site's most prolific generators of customer reviews. He is, in fact, a Top Ten Reviewer. This designation reflects not just his output (eight hundred and seventy-nine reviews, at last count) but also other people's reactions to it. When you read a customer review on Amazon, you can vote on whether you've found it helpful. McInerney's ranking--No. 6, to be precise--indicates that users have found him to be more helpful than all but five of Amazon's hundreds of thousands of amateur critics.

McInerney is a forty-one-year-old commercial-real-estate-development executive (currently between jobs) who lives with his wife and two kids outside Springfield, Massachusetts. On the phone last week, he provided a glimpse of the cutthroat world of online literary politics, noting, for example, that other reviewers sometimes create multiple e-mail accounts and repeatedly vote "not helpful"on his reviews in an attempt to catch up with him. "As soon as Amazon started ranking people, everything in human nature that's associated with being competitive came out,"he said.

McInerney's first Amazon review, in 1997, was of Robert Ludlum's "The Matarese Countdown"("Wonderful book, may you write dozens more!”), and his most recent was of "The Da Vinci Code"("A riddle wrapped in a mystery inside an enigma, as Sir Winston Spencer Churchill once wrote. . . . A fantastic ride”). He said that he reads about a hundred and fifty books a year, and his body of work suggests an omnivorous appetite: biographies, thrillers, histories of science and art, mountain-climbing yarns, and anything relating to "Star Trek"or "Star Wars."He doesn't write many negative reviews, but he can occasionally be ruthless, as in a 1999 review of "The New New Thing,"Michael Lewis's story of the entrepreneur Jim Clark ("Jim Clark does nothing except whine, complain, whine, and then complain some more. . ...