Eye magazine did a recent article on iconic designs that had missed the history books (See Eye 68: Beyond the Canon). One of these forgotten heros was Playboy magazine. Back in the fifties the concept a risqué mens magazine was very different than it is today. Not only was this reflected in the features, but also in the cover design. A perfect example of just what a battle being risqué was is the feature in the April 1966 issue on what you had to do to get a cover approved. It's a great read and a great layout. Below are some great examples of how Arthur Paul focused on clever ways in which to show the rabbit brand.
More vintage covers can be found here and here or if you're really into it, then Playboy have created this great DVD collection of every page and every cover from the fifties.