Where the marketing men and women of yesteryear may have turned to gimmicks and the like to promote their products, contemporary advertising actively embraces the concept of getting ordinary, unaffiliated consumers to do your publicity work for you - and its easy to understand why.

The idea of being able to trigger millions of dollars worth of publicity with a relatively small actual expenditure is just too tasty to ignore, especially for small business owners and entrepreneurs who wish to generate a large amount of publicity with a relatively small amount of actual cash.

However, the modern-day King Arthurs of business are finding that a successful campaign is not just as attractive as the Holy Grail, but just as difficult to actually locate.

Modern advertising is rife with examples of the viral campaigns that weren't, from Budweiser's attempt at Internet television to a Burger King campaign that featured a rock group dressed as chickens. It's clear that establishing the word-of-mouth buzz necessary to sell a product or service requires some real savvy from would-be trend-makers, so gaining that knowledge should be a first priority.

The first point to understand is the basic division between the two types of viral marketing, product-based campaigning and ad-based campaigning.

The first is relatively simple in theory but extremely difficult to engineer. The basis behind it is the idea that, quite simply, if a product or service pleases consumers, they will tell their acquaintances about it.

While the concept of making a quality product that consumers appreciate is common sense, this type of buzz is nearly impossible to control simply on a mathematical level.

According to the book Secrets of Mouth Marketing by George Silverman, a person who is pleased with a product or service tells three other people about it on average. Someone who is displeased with a product, however, tells about eleven people. This means that unless a company can please about three out of every four customers or more, a very respectable satisfaction level, word-of-mouth marketing can only hurt their reputation.

If this seems like a public-relations nightmare, then ad-based viral campaign may be a better choice.

Ad-based viral campaigns try to spark viewer interest in advertisements themselves in order to draw attention to their products. While these are sometimes based solely on the web or on broadcast services, more often than not, ad-based viral campaigns try to link the images they display on television to viewers' "real lives".

A good example would be the "Joga Bonito", or "Play Beautiful" campaign that Nike ran in the lead-up to and during the 2006 FIFA World Cup. The advertisements, which featured Nike-attired Brazilian stars Ronaldo and Ronaldinho showing off their command of the ball while French soccer legend Eric Cantona lectured viewers on the value of athletic passion, had all the components necessary for a great campaign.

The advertisements themselves wowed soccer fans across the country with the players' technical wizardry. They aired during the World Cup, the one time when Nike could be certain that just about all of the world's soccer fans would be focused on their television sets. Most importantly, interested web-surfers would find themselves on a "Joga Bonito" website with a custom-designed web community and information about local 3-on-3 mini-soccer tournaments.

Not unexpectedly, the campaign captured viewers' attention and may have been a factor in the reversal of a streak of lackluster returns for Nike.

While viral marketing is a difficult field in which to conduct business, a successful campaign can help stretch a minuscule advertising budget enough to create massive public attention. With the right know-how and patience, a word-of-mouth campaign are the smartest way to make the customers work for you.