Most people like to be recognized for a job well-done. A bonus, a free dinner, even a certificate saying we accomplished something. But there's a whole class of workers who do NOT get noticed, precisely because they're doing their jobs. And when they mess up, that's when we learn of their very existence. Think interpreters, fact-checkers, and anesthesiologists. David Zweig profiles these people and their work in his book Invisibles: The Power of Anonymous Work in an Age of Relentless Self-Promotion.