Though the ROI has been widely accepted, Forrester Research has questioned the reigning idea that it comes at little or no cost.

In a study titled The ROI of Online Customer Service Communities, Forrester found that a company with 500,000 customers will likely need to invest up to $1.2 million in social networking over the first three years, CBS Interactive blog SmartPlanet.com reported.

However, the good news for small business owners is that the high ROI still makes it a worthwhile investment - that company can expect to see returns of approximately double the investment in the first year, followed by similar returns in the following years, the blog reported.

An often-ignored benefit of social media that contributes to this ROI is the customer service aspect, said the article.

Users that are extremely engaged in the business's social network are often motivated - and knowledgeable - enough to help other users with customer service questions and issues:

"Super users in the community often are the ones that have the product expertise to solve some of the most difficult customer questions," quoted SmartPlanet.com from the Forrester study. "The value of call deflection can be measured by looking at call volumes before and after the community is deployed; the savings are measured by multiplying the cost per call by the number of calls deflected."

The explosive growth of social networking sites is an added incentive to develop a social media marketing strategy - a recent analysis by iStrategyLabs found that Facebook had a total growth of 70.8 percent in the last six months, representing a total of almost 72 million new users.