I finished re-reading the book today. I'd forgotten that Harry used an illegal curse in this book. He used it on the LeStrange woman...she had used it on Neville's parents and on Neville at the Ministy break-in. Voldemort had used it on Harry so he knows/knew how it would feel. I wonder if it'll be in the movie?
The eerie green cover of book six shows Harry and Dumbledore looking into a pensieve giving it the look of a history book, which in a way, it is. The examination of Tom Riddles heritage and the history of how he came to want and use the dark forces of magic to accomplish his self centered goals.
The cover of book seven looks like Harry is sitting on his broom reaching for a snitch. Not sure how that goes with the title, Deathly Hallows.