Think about how a virus spreads from one person to another. One person gets sick and just by sneezing they can give the virus to many more people? those people get sick and share their germs with everyone they know and the next thing anybody knows is that there is an epidemic. That is the very concept of viral marketing.

The idea is to get everyone to spread your marketing message around because they want to. Now let's look at using an "folksonomies" in your viral marketing campaign.

A new consumer phenomenon is called "tagging" or "folksonomies" (short for folks and taxonomy).Tagging is powerful because consumers are creating an organizational structure for online content.

Folksonomies not only enable people to file away content under tags, but, even better, share it with others by filing it under a global taxonomy that they created.

Here's how tagging works. Using sites such as del.icio.us - a bookmark sharing site ? and Flickr - a photo sharing site - consumers are collaborating on categorizing online content under certain keywords, or tags.

For instance, an individual can post photographs of their iPod on Flickr and file it under the tag "iPod."

These images are now not only visible under the individual user's iPod tag but also under the community iPod tag that displays all images consumers are generating and filing under the keyword.

Right now Flickr has more than 3,500 photos that are labeled "iPod."

Tagging is catching on because it is a natural complement to search. Type the word "blogs" into Google and it can't tell if you are searching for information about how to launch a blog, how to read blogs, or just what.

Large and small sites alike are already getting on to the folksonomy train. They are rolling out tag-like structures to help users more easily locate content that's relevant to them.

Although tags are far from perfect, marketers should, nevertheless, be using them to keep a finger on the pulse of the American public.

Start subscribing to RSS feeds to monitor how consumers are tagging information related to your product, service, company or space. These are living focus groups that are available for free, 24/7.

Folksonomy sites can be also be carefully used to unleash viral marketing campaigns - with a caveat. Marketers should be transparent in who they are, why they are posting the link/photos and avoid spamming the services.