The Harry Potter books. I know they're children's books, but they're the best books I've ever read. Ever tried reading the whole series non-stop? I have. Weirdest experience! When you finish book 7 you have no idea what to do next. I'm currently re-reading the series again and I hope I can finish it before July 15. I'm now reading the Order of the Phoenix and I'm on page 443 so I think I'll make it ;-)
I read the first book by myself but I read 2, 3 and 4 with my mother. We took an awful lot of time for it just before I went to bed. The rising of Voldemort was the scariest part of all books together. I was 8 at the time and didn't want to read any further because I didn't know what to expect and book 5 wasn't out yet, so I really didn't know.
Book 5 wasn't easy too.. I didn't quite like the lawsuit.. I thought he was going to be expelled so I asked a random woman in the train (I saw her reading the book) if he was gonna be expelled or not. Luckily he wasn't!
The weirdest book I've read was Deathly Hallows. I couldn't believe it was the ending. I liked it but it was strange... I had the same feeling as I have now, it feels like somebody's dying and I can't do anything about it. No, I cannot describe it. The feeling got really strong when I read the epilogue. At first I wasn't quite happy with it but now I got used to it I really really appreciate it because we, the fans, now know that all is well :-)
By the way, J.K. Rowling made a special announcement yesterday. "Potter More". She's gonna do something Harry again...
Whether it is an eighth book, the encyclopedia, an actual school like Hogwarts... Nobody knows.