New York-based word-of-mouth marketing firm Buzz Metrics is among the leading players in tracking how online trendsetters and influencers can ruin a company's reputation using off-the-shelf technology available at any local electronics superstore. The marketing world calls them "determined detractors," but executives of once-proud brands brought to their knees call them "reputation terrorists." After all, says one advertising executive, "One determined detractor can do as much damage as 100,000 positive mentions can do good."

In one of the best-known cases, two brothers who live in New York City created a Web site complete with a three-minute video clip in late 2003 to protest the fact that dead iPod batteries could not be easily or cheaply replaced. There are countless other examples -- as Internet influencers take on corporate icons like McDonald's, Starbucks and Microsoft. In some ways, these passionate anti-brand efforts are simply a natural backlash against buzz marketing.