Pity the person who answered the phone when Heather Armstrong tried to get her washing machine fixed for the fourth time in two months. According to Armstrong, a surly customer service rep for Maytag said she didn't care that Armstrong had 1.5 million followers on Twitter. But Maytag ended up caring after Armstrong's angry tweets about the machine went viral and caught the attention of the media.

Now that ordinary people can use social media as a megaphone, companies are trying to find ways to avoid public-relations debacles like the one caused by Armstrong's Twitter tirade in 2009. At the time, if Armstrong hadn't have mentioned her following, Maytag would have been hard pressed to find out about it. But in the past two years, a handful of startups such as Klout and Peer Index have developed ways to measure a person's social-media capital and then feed that information to companies in real time.