Byron Katie - Loving What Is
This is a good book to get started with questioning and/or talking back to your thoughts. I'm interested in generalizing this approach along with the Sedona Method, since both approaches are essentially structured sequences of questions, and seem to fall under the broader category of NLP language patterns.
David Deida - The Way of the Superior Man
Great discussion of life purpose. DD's writing is poetic, flows well, and is inspiring to read. Obviously aimed at men, or those with a masculine mind-set, in particular.
Robert Scheinfeld - Busting Loose From The Money Game (on subjective reality)
Some cool mind tricks/exercises for reclaiming power from your fears of financial scarcity, but the exercises could well be applied to relationships, work, and other situations.
Julia Cameron - The Artist's Way
An inspiring book with lots of suggestions of exercises and practices to stimulate creativity, including the famous "morning pages"
The Basic Tools