Success Maniacs! - It's C.R.A.Z.Y. That Everyone Isn't Successful!

These are the two modern father's of motivational books and materials. I doubt there are many speakers and coaches in the world of motivation and training that were not influenced by these two men.

Think and Grow Rich This is the first book for anyone who wants to improve themselves.
Success Though a Positive Mental Attitude Second book to read. It is a follow-up of sorts to Think and Grow Rich. A definite must read after Think and Grow Rich.
Grow Rich! With Peace of Mind
Succeed and Grow Rich Through Persuasion
The Masterkey to Riches
You Can Work Your Own Miracles
A Year of Growing Rich Excellent day by day quotes from the wisdom of Napoleon Hill
Positive Action Plan
Keys to Positive Thinking
Keys to Success