There are lots of books on the market! Here are the ones I have found useful:

The Real Book

This book until recently was illegal, as it was produced (by students at Berklee in Boston, so the legend goes,) before the arrival of good legal copies of jazz compositions. Its photocopied nature plus various inaccuracies gave rise to the term 'fake book'.

The New Real Book

Like the Real Book only legal! There are now several editions in the Chuck Sher publishing catalogue.

Modern Method for Guitar: Volumes 1, 2, 3 (also available as one volume: Modern Method for Guitar Complete)
by William G. Leavitt
Hal Leonard Corp Paperback

This book is very dry, but offers you a bread and butter method for building a sound knowledge of the fretboard, and of guitar-playing generally. It's the world's first complete plectrum guitar method, and still the best, I think.

Melodic Rhymthms for Guitar
by William Leavitt
Berklee Pr Pubns Paperback
November 1, 1986

This is great for helping you learn to play and read quaver rhythms. It also helps the student develp a jazz feel.

Reading Studies for Guitar (positions one through seven and multi position studies in all keys) ~William G. Leavitt, William Leavitt (Composer)Berklee Press Publications Paperback - November 1986

This is a must if you want to learn to read music on the guitar.

Advanced Reading Studies for Guitar ~William LeavittBerklee Pr Pubns Paperback - November 1, 1986

This is similaar to the above book, except covering positions 8 to 12.

The Advancing Guitarist
by Mick Goodrick

This book is great for improving your lateral thinking about music and guitar.

Pentatonic Khancepts
by Steve Khan
Warner Brothers Publications Paperback
October 2002

On electric guitar I started out as a rock and blues player, so the first scales I learned were the pentatonic scales, which sit so nicely on the fretboard. This book helps the student apply these scales in a fresh way, to give a really colourful sound to them. There are certain substitutions that sound absolutely cool as soon as you apply them, e.g. play Bm pentatonic over Cmaj7, or Bbm pentatonic over G7.

Contemporary Chord Khancepts
by Steve Khan
Warner Bros.,U.S. Paperback
March 1997

I really like the books by Steve Khan - he has such a personal writing style, that I feel he is right there supporting me as I learn. His chord book gets completely away from the chord dictionery approach ('here are 24 shapes for G7b5' etc.) and offers a very practical and contemporary way of utilising knowledge that is already quite simple. The backing CD is a very useful part of this pack.

Thelonious Monk Fake Book
Music Sales Limited Paperback
May 13, 2002

Study (pianist) Monk's music thoroughly and you are well on your way in your study of jazz harmony, rhythm and melody.

Where to buy materials
A good supplier is Jazzwise at www.jazzwise.com

What not to buy
I advise you not to buy a chord dictionery. I got one years ago and have never used it. Worse, it can simply be confusing or else discouraging. The best way to build an extensive knowledge of chords and harmony is to learn jazz tunes from fake books and methods as listed above.