For the last few years, marketers have been obsessed with creating word of mouth and buzz to compensate for the declining effectiveness of traditional advertising. There have been several books on this important subject (including The Tipping Point), but none with the real-world insights that Dave Balter offers as today's leading practitioner of word-of-mouth marketing.

Balter's company, BzzAgent, has grown exponentially in just a few years; it now coordinates an army of 75,000 volunteers who talk up products they genuinely love, ranging from books, beer, and jeans to perfumes, restaurants, and sausages. These agents are not asked to follow a script when talking with friends and acquaintances in everyday conversations, nor do they conceal that they're agents. The honesty of their opinions is what make these agents believable.

The big lesson of BzzAgent's success is that companies don't need to win over experts, “influentials,” “cool hunters,” or “magic people” to drive word of mouth. They just need to reach ordinary consumers—from all age groups and income levels—who might be excited to try out new products before they hit the market. The person who sits next to you at work might have a bigger influence on what book you'll read next than any critic, or even Oprah.

Grapevine features many real Bzz Agent campaigns (and transparently highlights both successes and failures) to show readers what strategies work best in driving word of mouth. It's both a practical book for business people and an enlightening read for anyone curious about why products take off or flop.