Something I introduced in my campaign recently that I thought might be worth sharing as we got some good situations out of it (thanks of course to HP Lovecraft):
The Lexicon Mortis is sentient book of Magic (Lawful/Evil) with it’s own objectives (relative to your campaign) and a human face capable of speech on the front cover.
The book allows the owner to cast any spell that appears in your own sourcebooks. However casting a spell requires a saving throw vs. magic. Failure means the owner becomes possessed by the book and will be their slave.
A suitably disturbing image of the book is here:
http://www.epilogue.net/cgi/database/art/view.pl?id=43858&genre=2
A simple concept - but one that doubled the drama when the PC’s found themselves in a very, very tight spot…
Magical Properties:
New Submissions



January 3, 2004, 20:30
January 4, 2004, 4:29
November 11, 2005, 17:43
September 2, 2010, 18:50
July 17, 2011, 3:46
I see no real reason to make the book intelligent, but I do like the risk/reward balance it presents. It's also very powerful, and the limitations are not very well defined though I suppose that is intentional. This makes a better idea than a submission.