The covers of the Penguin UK James Bond novels are absolutely stunning. They are simply great triumphs of design. The photos are often unexpected stills from the films (only the Sean Connery films...) which manage to play off the history of both the films and the novels.
Check out the cover to Thunderball, which shows a Sean Connery so gaunt and tired that he's almost unrecognizable. The Bond character in the novels gets tired, he messes up, he gets hurt and he doubts himself; you don't really see that in the films, but this cover photo grabs it.
Yet, despite how beautiful the books are, there's no denying that I get weird looks on the bus when I'm reading a novel with a naked Ursula Andress on the cover.
Check out the rest of the covers here:
AND: they've actually all been redesigned in the past couple of years, but using the same photos, and you can see those here.