I only found out this past week that Melissa Anelli, the webmistress/creator of the-leaky-cauldron.org, has written a book about the history of the Harry Potter phenomenon. It's called Harry, a History, and it chronicles the craziness that is the HP universe. It looks like a fun book, but I'm waiting for its release at the library.
More importantly, The Tales of Beedle the Bard is set to be released in less than a month! There's a gorgeous collector's edition available on amazon, but it's $100! I think I might just settle for the standard edition, which might not be as beautiful, but will be just as entertaining at a fraction of the price!