A librarian's dream, a floating book knows its name and comes when called. Designed by academic magic users, floating books are difficult to lose and rarely out of reach.
Much like an armor or weapon special ability, the floating quality can be added to any masterwork book or spellbook.
A floating book hovers approximately 3 feet above the ground at all times and remains in the orientation its owner sets it. The book floats horizontally and unless commanded otherwise accompanies it's owner. Placing any weight on the book causes it to fall.
Faint Evocation; CL 3rd; Craft Wondrous Item, Tenser's floating disk; Price +500gp
Source: Dragon 341 Pg 65