User-generated content enables a firm to leverage marketing's best tool: a satisfied customer. Social networking greases the skids of consumer reviews by emphasizing the ratings and reviews that users care most about-- those from their friends.

Users on Yub.com, an online mall where people meet, chat and receive up to 25 percent discounts for shopping, create large networks of virtual friends. The user's opinions are automatically sent out to all of their friends as a "rave." The brand is on all communications and the social network encourages users to return to the site often.

Yub.com creates large networks of virtual friends that share product ratings and reviews.

Next: Conclusion