Yelp! is a social networking website where users create their own profiles, invite friends, and post review of businesses. 

Yelp provides access to candid reviews from consumers and does not rely on advertisers.  Users themselves rate businesses and essentially learn more about products from fellow Yelp users.

Companies can build strong relationships with WOM buzz on this site.  Also, users enjoy the fact that users' information is not sold to advertisers.

However, competing companies can damage each other through false reviews.  Clearly, bad reviews can damage the brand reputation of certain companies among target consumers. And the site does not allow companies to improve their shortcomings.  Notably, business-to-business companies are not reviewed on the site.

Nonetheless, companies are finding that this site can be a tool for WOM advertising and viral promotion.