Yahoo! announced it was buying web analytics business IndexTools, setting the stage for Yahoo to offer an answer to Google Analytics.

Google bought the Urchin business in 2005, and set the web analytics industry on its ear by rebranding it as Google Analytics and giving it away free. Google Analytics is now used by hundreds of thousands of businesses and organizations -- including, says Google, scores of Fortune 500 companies.

Critics note that the software may be "free," but that Google Analytics users give Google something of significant value: data about merchants' traffic, paid search conversion rates, average order values, and more. All that data tells the ad-selling side of Google's business a great deal about how much higher click prices can go before they become uncompetitive with other direct-response advertising media.