As you can see, the UK reissue of The Revolt of the Eaglets has quite a clever variation on the ever-popular headless woman cover:
Maybe this will start a trend--I see possibilities for all sorts of combinations here. Anne Boleyn with Purkoy, perhaps.
Speaking of covers, there's a nice gallery of them here at Fantastic Fiction. My favorite is the one from Red Rose of Anjou. It's probably safe to say that the hunky guy on the cover isn't Henry VI.