books that opened the door to exploring various spiritual paths

The Te of Piglet - Benjamin Hoff
Peace Is Every Step: The Path of Mindfulness in Everyday Life - Thich Nhat Hanh
Way of the Peaceful Warrior - Dan Millman
Bringers of the Dawn: Teachings from the Pleiadians - Barbara Marciniak
The Road Less Traveled - M. Scott Peck
Mutant Message Down Under - Marlo Morgan
Perfect Health: The Complete Mind/Body Guide - Deepak Chopra
Nothing in This Book Is True, But It's Exactly How Things Are - Bob Frissell
The Celestine Prophesy - James Redfield
Be Here Now - Ram Dass

must read books for beginning spiritual work

Zen Mind, Beginner's Mind - Shunryu Suzuki
Rudi: Spiritual Cannibalism - Swami Rudrananda
Yoga: The Science of the Soul, Vol. 1 - Bhagwan Shree Rajneesh
The Myth of Freedom - Chogyam Trungpa
Sadhana Guidelines: For Kundalini Yoga Daily Practice - M. S. S. Gurucharan Singh Khalsa
Taoist Secrets of Love: Cultivating Male/Female Sexual Energy - Mantak Chia
I Remember Union: The Story of Mary Magdalena - Flo Aeveia Magdalena
The Heart of Yoga: Developing a Personal Practice - T. K. V. Desikachar
Wonders of the Natural Mind: The Essence of Dzogchen in the Native Bon Tradition of Tibet - Tenzin Wangyal
The Joy of Sacrifice : Secrets of the Sufi Way - E.J. Gold