Printouts to help you play the game, such as Spell Summaries, Verbal Cheat Cards, and the Smithing Reference Sheet.
All In-Game books created by players, such as Manuscripts, Tomes, etc., are required to have an OOG disclaimer in them. This PDF file has the disclaimer pre-printed, so that it can easily be cut out and pasted into a book during creation.
A handy summary for Smiths, two sides of one sheet of paper. This includes the changes for March 25, 2014.
"You do realize I could do this all day..."
~Erdrick (who was out of Magic Points at the time)