Randy Halberstadt

This is absolutely the best book I've every read for improving your jazz playing. It's good for any instrument, but especially jazz piano.

I've recommended it to every beginning jazz player I know, and some have purchased it and loved it.

Don't let the "pianist" part of the title fool you. If you're interested in jazz and improv., I'm sure you'll be able to make use of this book, like me.
I'm not a very proficient pianist, (I'm a saxophonist) but the ideas that come out in this book helped me improve my improv. greatly. My understanding of chords increased greatly, and I gained more confidence for my solos. This book has changed my life in terms of music, and I doubt it will not change yours either.

An excellent presentation of ideas for the practicing jazz musician. I really enjoyed his deconstruction of chord voicings and his interesting thoughts on motif development in solos.