Pema Chodron, These two books and everything else by Pema Chodron. www.pemachodronfoundation.org
Robert Monroe, The Monroe Institute
Raymond Moody, Life After Life
This is one of the first books that broached the subject of what happens after we die as a research project.
Deepak Chopra, www.chopra.com
David Spangler, www.lorian.org
Joel Osteen - Joel's work is all about encouraging people to claim the truth of their souls and receive the grand life that becomes possible when you accept your soul power.
Shakti Gawain, http://shaktigawain.com
I love Shakti Gawain. She has her own unique style and amazing clarity and integrity. I recommend all her books. Here are two that had a big influence on my life.
Psalms for Prayer, An Invitation to Wholeness, Nan C. Merrill
This is a beautiful book. It takes the psalms from the Bible and takes away the arcane language and replaces it with spiritual concepts. For example "enemy" becomes fear. This book is full of power, truth and inspiration. It instantly sets up a clear space of Truth and God. I love it.