One morning in April, we each directed our browsers to Amazon.com's website. Not only did the site greet us by name, the home page opened with a host of suggested purchases. It directed Joe to Barry Greenstein's Ace on the River: An Advanced Poker Guide, Jonah Lehrer's Imagine: How Creativity Works, and Michael Lewis's Boomerang: Travels in the New Third World. For John it selected Dave Barry's Only Travel Guide You'll Ever Need, the spy novel Mission to Paris, by Alan Furst, and the banking exposé The Big Short: Inside the Doomsday Machine, also by Michael Lewis. By now, online shoppers are accustomed to getting these personalized suggestions. Netflix suggests videos to watch. TiVo records programs on its own, just in case we're interested. And Pandora builds personalized music streams by predicting what we'll want to listen to.