This is a little off-topic, but I have the COOLEST poster from the first movie!
I was studying abroad in London when the first movie came out, so my friend Merry (who is obsessed as I am, if not more so) and I headed down to Leister Square the day of the premiere. The theatre is HUGE and was all decorated as Hogwarts, with big house banners hanging up. It was a really neat experience, we saw JK Rowling and a bunch of the actors coming to see the movie (we saw Harry, Hermione, Ron, Fred and George, Crabbe and Goyle, Hagrid...) and it was really cool.
So they had these big posters hanging on all the barriers, and they had a stack of leftovers they were handing out at the end - so Merry and I each got one of those. And a few weeks later, Alan Rickman came and talked to one of my classes (I know, you're all jealous!) and so I got him to sign it!
The neatest thing is that it says "The Philosopher's Stone" - everyone looks at it and asks "Why doesn't it say Sorcerer's Stone?" And then I get to tell my London story!