It's ironic that the growing sophistication of marketing communication should be precipitating a revival of interest by brands in the world's oldest form of communication - speech.
Last week, word of mouth took a further step towards being accepted as a mainstream marketing discipline by being included in the IPA's TouchPoints survey of media consumption for the first time - the association also hosted a seminar intended to underscore the discipline's growing importance.
This is all being undertaken in an attempt to help the UK catch up with the US, where WOM is predicted to become a $300 billion industry by 2012.
The Chicago-based Word of Mouth Marketing Association has around 400 members including major advertisers, such as PepsiCo, WOM marketing specialists and mainstream agencies.
"WOM is moving from an emerging marketing discipline to an enduring one," John Moore, a senior WOMMA executive, says. "People have always talked to each other about brands and products they loved or hated. But this has almost always happened serendipitously. Not strategically, as it does now."
Of course, the social networking explosion has given a huge impetus to WOM - and that's bound to increase in the coming years with the expansion of mobile internet technology - but the fact remains that only 10 per cent of WOM activity currently takes place online. Twenty per cent is via the phone and 70 per cent is still face to face.
Meanwhile, WOM is broadening the role of PR, with agencies now just as likely to be targeting influential bloggers as journalists. "WOM enables us to listen and learn," Alan Parker, the head of dialogue at the PR company GolinHarris, says. "It's about trying to skew the conversation."
Although the first WOM specialist agencies began appearing in the UK more than a decade ago, it was the arrival of Facebook and Twitter that gave the discipline a new dimension. At the same time, the fragmentation of media made advertisers begin looking at WOM as a more cost-efficient alternative.
In essence, it is a form of promotion in which satisfied customers become "ambassadors", telling other people how much they like a business, product or service.
Molly Flatt runs 1000heads and is the president of the Word of Mouth Association UK. She says: "Your biggest-spending customer may not necessarily be your most valuable. It's the one that recommends you the most that is a real asset to your business."
WOM isn't like advertising but its enthusiasts claim doing it well can not only reinforce an advertising message but provide intelligence to those responsible for everything from packaging to product research and development.
The consensus is that agencies need to decide at the outset of a campaign how WOM can best be used to increase its effectiveness and to get consumers in a positive mood before the advertising starts. Ivan Palmer is the chief executive of Wildfire Word of Mouth, a Grey-owned business working on the new "live every litre" campaign for Honda. He cites Procter & Gamble's Pringles brand, which organised a mass-tasting programme for a new rice-based snack - before any advertising began - to address consumer perceptions that such a product wouldn't taste good. He claims a campaign's effectiveness can be increased by 10 per cent if WOM is effectively integrated.
But there's a price to be paid. "Brands will never have control of the conversation and have to accept that," Flatt says. "You have to be OK about negative feedback."
What's more, transparency must be total. Palmer warns prospects: "If you have a product that doesn't do what you claim it will do, then don't come to us."
Specialist agencies also claim it's often difficult to convince brand owners that going the WOM route isn't just a cut-price alternative to mainstream advertising. "Brands have to realise that WOM is neither free nor cheap," Flatt says. "Like an investment in a microsite or a TV ad, WOM is an investment in a relationship with people."
Creating a credible system of calculating a return on investment from WOM is also still work in progress, although Flatt claims it's now possible to calculate the value of a brand's "consumer sentiment" and that software is being developed that's capable of measuring what sort of feelings consumers have towards particular brands.
The other key question is whether WOM and advertising can be made to work in tandem. "There has to be empathy between them," Flatt says. "WOM's big advantage is that it can tell a company what people are saying about its ads." Parker believes WOM can actually enhance the success of a TV campaign if interest has already been stoked up by running it online first.
However, Moore is convinced that it's in the area of customer service that WOM will really come into its own. Comcast, the US cable operator, aims to act instantly over any online complaints about poor service in the hope that a disgruntled customer can be turned into a brand "ambassador". It's an example lots more organisations may soon be following in the UK.
PepsiCo (Pepsi Refresh project)
The Pepsi Refresh project, which began in the US at the end of last year, has been inspired by belt-tightening consumers who are opting to spend their money on brands that show responsibility and help improve the world.
The initiative is an extension of a Pepsi marketing programme under the theme "refresh everything", where people are asked to talk about ways to change the world.
Now PepsiCo has put up $20 million to fund community projects across the US. Using a heavy social media presence, the soft drinks giant is asking people to list their suggested projects online and to vote for the winners.
PepsiCo is partnering with several groups to run the programme while other groups will administer the grants. A website for the project, www.refresheverything.com, launched last month.
"Clearly Pepsi's hope is that this will make consumers think more positively about the brand in a highly commoditised cola market," John Moore, a senior executive of the World of Mouth Marketing Association in the US, said.
Terry's Chocolate Orange (Whack and Unwrap)
Dawn French, the long-time ambassador for Terry's Chocolate Orange, used to tell TV viewers: "Don't tap it, whack it." Last year, the Kraft-owned brand took the idea into new territory to get itself talked about in the run-up to the Christmas sales period.
GolinHarris set up a branded Facebook page and partnered with the comedian Dom Joly to launch a "Whack and Unwrap" competition through a series of viral videos hosted on YouTube.
The competition encouraged people to film clips of their favourite "whack and unwrap" methods. A series of "street" films were also produced showing consumers "whacking and unwrapping".
The videos were used for digital, outdoor display and online banner advertising, with the winning film shown on the big screen at London's Piccadilly Circus.
More than 80,000 people visited the Facebook page with an average of 400 interactions a week. The YouTube channel has received more than 220,000 views to date.