The rising popularity of a German online ad blocking application poses so great a threat to the web content business that one site is encouraging publishers to bar Firefox users altogether. Adblock Plus, an open-source extension for the browser that whites out banners and keyword search advertising, now has 2.5 million users and is adding up to 400,000 more every month, developer Wladimir Palant of Cologne tells the NYT, which suggests, at that rate, the practice could become the web equivalent of DVR ad skipping - a revenue killer.

Grumbling about Adblock Plus in particular, an anonymous new campaign, WhyFirefoxIsBlocked.com argues that ad blocking is “stealing”, says publishers have a right to ensure visitors see their ads but, because they cannot block users of individual Firefox extensions, encourages site owners to blanket-ban Firefox users en masse. It reckons the move would have “only minimal financial drawbacks” because Firefox users are a minority. As yet, there appears no sign publishers are resorting to such militancy (CNN.com and Google gave the Times a no-comment), and there is a counter-campaign at WhyIsFirefoxBlocked.com. Palant previously wrote: “There is only one reliable way to make sure your ads aren’t blocked — make sure the users don’t want to block them ... Use ads in a way that doesn’t degrade their experience.”