I just joined YPN and have never display ads on my site. Is it possible to list 10 ads in a row like a search engine would display? I've seen some portals that do similar formatting with Overture ads. Is this type of layout possible?
You can't alter the ad code in any way. Premium publishers (very large sites) can get special approval for different formats. You can display more than one ad block, so the closest you could come would be stacking some existing ad formats.