I just tried putting Yahoo on a new topic and several pages have just one ad centered on the skyscraper.
I suppose it might be they just don't have enough ads but then it seems like sometimes there would be 2 or 3 ads, not always just one. Are these some kind of special ads? They don't seem to be RON as they are kind of targeted. (That is if you consider an article on mental focus to be related to cameras. I guess it's that you focus a camera too)
Actually a couple of other ads are well focused and one is way off. (Much as I try I can't see any relationship between creativity and small appliances.)