You know you love books when:
- You hesitate to buy books because you have run out of shelf space.
- You still buy those books, because you just know you can squeeze them in somewhere.
- You can't squeeze them in, so they end up balanced precariously on the edge of a shelf.
- Your library begins to impose a limit on the number of items that can be checked out on one card.
- The librarians know you on sight and know exactly where your books are on the hold shelf.
- You memorize your library card number.
- Your library card expires and you are dismayed to find out that you cannot keep your old number.
- Your pulse quickens during library book sale season.
- You buy books at library book sales just because they looked interesting.
- You walk out of library book sales carrying several large boxes of books.
- Your "to read" list gets increasingly longer.
- You can rattle off the release dates of a dozen new books on your wish list.
- Your relatives want to know if you would like anything other than books for your birthday or Christmas.
- People start to wonder if you can give any gifts that are not books.
- You constantly nag your friends to read more.
- You meet somebody for the first time, and the first thing you ask them is, "So, do you read much?"
- You plan on naming your children after your favorite characters from your favorite fantasy novel.
Yes, I personally have experienced every single one of these. 
Feel free to add anything I've missed!
Oh my goodness, I relate to Every Single One too. (So I'm not the only person to memorise my library card number? Wow.)
We're currently lookin' fer a new house, and usually the first thing I ask about a possibility is "Does it have a library near?" It's one of my dreams to have a library or bookstore within walking distance!
