My bud Alexis linked me Lucy Knisley's works the other day and I am (im)patiently waiting until she finishes up posters for the last three Harry Potter books so I can buy them all together and save monies. They're hilarious, adorable, and accurate. You can see one through four here, and purchase them here.
(Note: That kitty next to Hermione when she first shows up is not Crookshanks. Would I really link you something Harry-related if it weren't accurate? Come on.)