The end of free Internet content will come when Web browsers start blocking online advertisements by default, a DoubleClick executive has warned. Bennie Smith, the online advertising network's privacy chief, told ZDNet Australia the popularity of tools like Adblock -- an extension to the Mozilla Firefox browser -- which makes blocking online ads simple was tied to "a negative vibe against advertising in general". However, only the online arena is able to easily produce and widely distribute such tools, he added. He said if a similar tool could be produced for newspapers, it would not be accepted by consumers. "You'd...