"The basic premise of the product is that you need to control your search results," Fertik says. "The idea is that you want to control as much of a page one and page two for searches for your business name or people associated with your brand."

Reputation Defender also is testing a free reputation alerts system Fertik describes as "Google Alerts on steroids" -- a tool that continually searches for information about you online, even in content that doesn't show up on search engines.

For people and corporations who find out they are under attack via Twitter or in blogs, the best course of defense may be to acknowledge the attackers with blog posts of their own -- or, better yet, offer to help. Comcast ( CMCSA), saddled for years with a reputation for bad customer service, finally faced the problem head-on with its Comcast Cares campaign, in which the company employed full-time ambassadors to troll the Web for complaints about the company and reach out to the complainers with offers to help. Best Buy ( BBY) employs thousands of customer service reps to tweet electronics advice and engage customers in a program called Twelpforce. IBM ( IBM) and Dell ( DELL) also have thousands of employees tweeting on the company dime, Ochman notes.

"I'm astonished that people are still asking whether, if they see a bad blog entry about their companies, they should respond," says Anthony Johndrow, a managing director at Reputation Institute, a consultancy that advises major corporations about their reputations. "Of course they should respond!"

In April, Reputation Institute came out with a list of the most reputable large companies in the United States, based on consumer perceptions not only of the companies' products and services but of corporate governance and workplace policies, leadership and performance, citizenship and innovation. "We've talked to investors, and they care about these other dimensions too," Johndrow says.

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