The sale of Zappos to Amazon provides a definitive answer to a longstanding question. “What’s the precise value of excellent customer service?” The answer is an astonishing $900 million. Anyone can slap a pricetag of a pair of shoes. But Zappos transformed the seemingly counterintuitive concept of selling shoes online into a runaway success. Outstanding customer service- largely characterized by savvy use of social media- has resulted in an enormous payday. It’s only fitting.