Andrew, in fairness this is incorrect. Web advertising on content is no more, nor any less, effective than web advertising in a printed magazine. Rather than ask the question "How many of you have clicked on something and bought it." a more relevant question is "How many of you have bought something, or from someone, you have seen as an advertisement on a web page?" Digikey ads showed up on Dr. Dobbs and I've bought a ton of stuff from them. Sometimes reading an article there, will show an ad, and it will remind me of something I was supposed to get. Then I will go over there and buy it. Almost exactly as I did with the magazine version.

That said, click fraud has really burned a lot of advertisers. That is why advertising on content needs to shift to a performance based model, ads that let you know that someone went to a site after they saw the ad on your page, and bought it. That should net you a few $. As it stands, advertisers bid for 10,000 clicks at a nickel ($500 ad spend) and compare that to what they sell, and they come up poorly. If they set aside $500 to reward the first 100 people who clicked through and bought something you would find things to be very very different. Click fraud doesn't work if the value isn't in the click. But this migration is currently not happening as quickly as we would like.