J.K. Rowling liberally sprinkles book titles throughout the series, and I've posted a new poll listing some of my favorites. There are 60 books listed, so it doesn't contain every title mentioned in the series (if you're looking for that, see this list at the Harry Potter Lexicon.) But, if the book is featured in my poll, it means that it figures significantly into the plot. Or it's on Harry's initial shopping list in Sorcerer's Stone. Or I think the title is cool. Clearly, I used rigorous standards.