Books

Also see:

Akashic Records: Mystical compendium of all knowledge.
Big Book of War: A fictional book about war, battle tactics, martial code that's often referenced in an offhand manner.
Blank Book: A book with no contents.
Book and Switch: Someone tries to hide the book they're actually reading behind another book to trick others into thinking they're reading the outer book.
Book Burning: Books are burned for ulterior reasons.
The Book Cipher: Books are used to code messages.
Bookmark Clue: Important information is discovered being used as a bookmark.
Book on the Head: Balancing a book on your head in order to improve your posture.
Book Safe: A hollowed out book is being used as a “safe” for certain items.

Bookshelf of Authority: Posing a character in front of a bookshelf to show that they're smart.
Book Snap: A character slams a book shut to show their anger or seriousness about something.
Books That Bite
Books vs. Screens: A False Dichotomy between reading and TV/computers, usually either "if you like one, you can't like the other" or "books are better".
But I Read a Book About It
Conveniently Interrupted Document
Deadly Book
Diary (and Secret Diary)
Doorstopper
Extremely Overdue Library Book
Faux-To Guide
Flying Books
Great Big Book of Everything: A book that has information on any subject the characters may try to look up.
Instant Book Deal
The Magazine Rule
Newspaper-Thin Disguise
Parodies for Dummies
Portal Book
"Reading Is Cool" Aesop: The story has the characters learn that reading doesn't have to be boring.

Reality-Writing Book
Rewriting Reality
Rushed Inverted Reading: A character hurriedly grabs a book to make it appear that they were innocently reading, but the book is being held the wrong way round.
Sacred Scripture
Significant Sketch Book
Specific Situation Books
Spell Book
Throw the Book at Them
Tome of Eldritch Lore
Tomes of Prophecy and Fate
Useful Book: A book gets used for a purpose other than reading it.

Libraries

Great Big Library of Everything: A library that has books on every subject imaginable.
Spooky Silent Library
Bookcase Passage: A secret passage hidden behind a bookshelf that is revealed by lifting one of the books.
Magical Library