The concept of word of mouth (WOM) has been generally ignored by practitioners and academics alike. While its power has been acknowledged for more than 50 years, marketers regarded WOM as a happy accident and an occasional fortuitous addition to their campaigns. But times are changing and a slew of recent marketing success stories suggest that WOM may prove to be the making or breaking of many brands in the years to come.

Advertising has traditionally been the closest marketers have come to WOM. Teaser campaigns attempted to stimulate it, while classic executions for products like WeightWatchers have tried to simulate WOM on the screen.

Research suggests, however, that advertising's brush may be too broad to create successful WOM impact. According to Renee Dye from consulting firm McKinsey & Co, 67% of consumer sales are influenced by WOM. However, she points out that to truly harness the power of WOM marketers must reach a vanguard of consumers who inhabit the first fringe of the adoption curve.

Marketers must stop thinking of their communication efforts as a single transaction (ad impacts market) and attempt instead to create waves of communication that spread from a small number of lead users through consumer-to-consumer interaction.

The process is tricky, but agencies are springing up to help clients.