Chitika, an ad network for bloggers, has released a self-serving and utterly ridiculous study estimating the blogosphere's revenues at $500 million. Shamefully, the University of Texas participated in the charade (PDF), relying on data from Chitika customers and Technorati popularity rank. Chitika's customer sample, of course, could be biased and flawed in a thousand different ways; why the UT-Dallas researchers didn't insist on a random sampling is beyond me. And Technorati, of course, measures the number of blogs that link to a blog — an interesting datum, but not one that correlates with traffic, or that advertisers particularly care about. A more realistic estimate?