For the benefit of those not yet so enlightened: The greatest man what ever lived, was Richard P. Feynman.  Many thousands are so aware, and there is a plethora of web space dedicated to him already.  I have no intention of competing with all of that.  Here I simply present some of my favorite books written by and about the man with the modest goal of introducing him to a few more souls.  Encountering Feynman is a potentially life changing experience.  Dividing forevermore one's life in twain; that which occurred before learning of his existence, and everything since.
The perfect introduction to the world of RPF.  This is an absolute must read for any thinking being.  A series of short, humorous stories makes for a very easy read you won't want to put down.
Billed as a sequel to SYJ, this is a book in two halves.  Pt. 1: The story of Dicks first love. A libretto in search of an opera.  Life imitates art.  Pt. 2: Dick investigates the Challenger accident and gives the finger (figuratively) to government bureaucrats.
Sykes' interviews for the BBC were used for the PBS NOVA episodes that served as my introduction to the man.  This book contains material not available in other works.  I found the contribution by his sister Joan to be particularly moving.
The definitive Feynman biography to my mind.  A fairly massive tome, well worth the investment.  This work serves as a vehicle to a larger thesis by Gleick.
Quantum Electro-Dynamics.  Written for the layman, Feynman teaches actual physics.  Learn the theory that explains all of physics except gravity and radioactivity.  A specific elucidation of iridescence should be of particular interest to fans of this site.
Originally transcribed from lectures to a freshman physics class, a failed text this set enjoys continued popularity amongst graduates.  Find out what you were really learning about. Once referred to as the 'Red Books', they are a required component of any personal reference collection.
     Once you are hooked on Feynman you will find a vast amount of material to satiate your appetite.  Be prepared to wade through a lot of repetition though.