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.

Wildfire, a London based WOM agency has developed a three-stage methodology: discovering the target groups, developing the key 'stories', then deploying these stories using events and direct marketing.

Another agency, Comment, was set up in South Africa for the millions of black workers who had little access to TV or radio and were largely illiterate.

When employers, unions or health organisations wanted to communicate with them, they used Industrial Theatre: song-and-dance based productions performed on the factory floor. Soon Comment was putting on live ads in cinemas and shopping malls for a variety of clients – a campaign for Organics shampoo saw handsome men serenading women in supermarkets.

There is of course a downside to all of this. The ultimate form of WOM stimulation is never revealed to be stimulation. Rather, hired protagonists engage in artificial behaviours and conversations in order to initiate the first wave. Glamorous students in London, for example, were paid to smoke and distribute Gauloises cigarettes to their peers. Even more infamous, Sony Ericsson paid people in the US to masquerade as tourists and ask people to take their picture with the then new T68i camera/phone. Unfortunately the campaign was rumbled by the US press and spawned a PR backlash against the brand.

Like all forms of marketing communication, WOM has advantages and limitations.

But for the first time the marketing industry is actively attempting to engage WOM as a strategic vehicle. In the cluttered communications world we all inhabit, there is a certain purity in returning to the oldest method of communications around.