Cable channels like HBO and NFL Networks are among the biggest users of addressable TV advertising these days -- "partly because paid TV services don't want to waste sign-up ads on people who already shell out for the product," but want the highly targeted views such ads provide, writes Jeanine Poggi. She provides case histories of how several channels used these ads to good effect, also noting that for other industries "the limits of the pay-TV systems' reach have held back widespread adoption" of addressable commercials.