Stephen Baker of Businessweek writes on Blogspotting that:
When advertisers research the effectiveness of an online advertisement, they typically populate half of the pages with the ad–and the other half, the control group, with a filler ad, a placebo. This is valuable advertising real estate that is often given away.
He ends the post by asking whether advertisers get to write-off this sponsorship of charities. Very good question–
Its sounds like an interesting little niche and I’ll try to explore it and hopefully come up with some answers for us. Stay tuned.