While Web marketers have long been tracking the growing influence of online consumer reviews, a study released in June from Opinion Research reveals the impact of these reviews has reached a tipping point.

The study found 83% of online shoppers said the evaluations and reviews they find on the Web are now influencing their purchasing decisions. Another 32% said they had posted feedback or a review of a product or service online.

"It's nearly impossible to escape being evaluatedthere's nowhere to hide," says Linda Shea, a senior vice president at Opinion Research. "Even a single negative review posted in a very public forum can have a significant impact on a prospective buyer's decision."

Thousands of reviews

Besides numerous blogs, there are many independent consumer review sites rating the petfood industry. You'll find thousands of reviews of petfood products on sites such as:

• HubPages ;
• Zootoo ; and
• Buzzillions .

Online retailers, including Petco and Dog-Foods.org , now include reviews along with product descriptions. Manufacturers like ProPac and Old Mother Hubbard are also getting in on the act.

Interestingly, some review site pioneers-heavyweight online retailers Amazon, eMusic and eBay-have decided to embrace reviews on their sites that are both positive and negative. These companies buy into the "brave new Web" theory that a company demonstrating complete transparency earns the greatest respectand most repeat businessfrom today's sophisticated online shoppers. Other sites seem convinced that by posting only glowing reviews, they'll be able to look trendy while bringing in more business.

Cost-effective feedback

Plenty of service providers specialize in the online review space to help companies build and manage online review domains or bring in turn-key systems that can be managed in-house.

"Blogs, discussion boards and other forms of interactive media are the most cost-effective customer feedback mechanism ever invented," says Paul Gillin, author of The New Influencers: A Marketer's Guide to the New Social Media .

Generally, these online review communities fall into three categories:

1. Social hang-outs (think MySpace or Facebook ), which offer a review domain component;
2. Completely private, invitation-only sites; and
3. Communities that exist solely to solicit reviews from extremely happy customers.

Cloning MySpace

Most popular are communities borrowing from the MySpace and Facebook model. Web marketers say you'll only be able to achieve that look and feel by offering a full array of community fostering features, including discussion boards, chatrooms, instant messaging, blogs, photo, audio and video posting.

You'll also want to jump-start the community's nerve center-the discussion board-by posting commentary on a dozen or so topics, then encouraging visitors to offer reactions and opinions to the discussions you've started.

Providers specializing in MySpace-type communities include Affinitive , Webcrossing and Capable Networks .

By invitation only

Communispace , an online community service provider that specializes in designing and helping companies run private meeting places, can help you build an invitation-only review site. While these are generally much smaller than public sites, many firms have discovered a big pay-off when they choose who will belong to their review community.

For the company

Some of the biggest names in business-including Dell, Macy's, Sears, Charles Schwab and PepsiCo-have sites that limit all review activity to public evaluation of the company's products and services. Many of these communities are driven by highly sophisticated review software packages, which walk visitors through every step of the process and encourage them to expound.

No matter which type of review community appeals to you, such gathering places will likely continue to appear. "Expect at least one-quarter of the Fortune 100 to announce online communities," says Brad Bortner, co-author of Top Market Researcher Predictions for 2008 from Forrester.