Ads for products I already use. Probably 90% of the stuff in your house has been advertised somewhere. A good number of the books on my shelves advertise other books by the same author in the back (some of these are order forms, many are not), and I certainly do use them to see what's the next book in a series of what reviewers have had to say about other books by the author. Heck, some of the objects I own and use daily (hopefully lower than average) is itself advertising, such as the branded Crayola desk lamp I'm using.