For years television networks have paid rapt attention to the Nielsen ratings to help guide programming decisions. But some networks have begun hiring new breed of ratings services that use the Internet to measure viewer engagement and "chatter" just as it bubbles to the surface.

One such service, Canada-based Brandimensions, says its robots, crawlers, and spiders traverse 20 billion Web links to fan sites, blogs, and chat rooms in a 30-day cycle to determine "buzz" rankings for TV programs. According to the firm's CEO, Bradley Silver, the service provides "a unique measure of viral energy."

As an example of how the two ratings systems offer differing perspectives on TV show popularity, Nielsen reported that "CSI" was the most-viewed show of a recent sweeps period while Brandimensions said "My Name Is Earl" produced the most Internet buzz. "Earl" commanded an 11.7 percent share of Web audience discussion and a 4.41 score on a five-point sentiment scale last fall.

The emergence of these new services raises a central question: Can anyone really track something as elusive as buzz? The TV networks have long tried to quantify viewer interest based on research other than Nielsen size estimates. The jury is still out, however, on whether Internet buzz tracking will be a dependable metric to gauge viewer response.

But if firms like Brandimensions and BuzzMetrics continue to make the case that online word-of-mouth research can be indispensable to networks, this emerging form of market research could become a new global standard for measuring and analyzing consumer buzz.