The following are some of my favorite yoga and related reading titles.
The Tree of Yoga and
Light on Life by B.K.S. Iyengar also recommended are Light on Yoga and
Light on Pranayama
A wonderful overview on yoga, the practice and philosophy for newcomers:
Living Yoga, a Comprehensive Guide to Daily Life by Georg Feuerstein
Living Your Yoga by Judith Lasater

The Heart of Yoga by T.K.V. Desikachar
Actually all books written by the two authors above are wonderful, Feuerstein is my favorite writer on yoga. Also good are his Yoga, a Shambhala guide and Yoga Gems.

Yoga and Ayurveda, Self-Healing and Self-Realization, by David Frawley
Anatomy of the Spirit by Caroline Myss
The Language of Yoga, A Complete Guide to asana names, sanskrit and chants by Nicolai Bachman

Beautiful Reading:
Autobiography of a Yogi; Paramahansa Yogananda
My Guru and His Disciple; Christopher Isherwood
Bhagavad Gita; translation by Stephen Mitchell (there are many other translations, of course.)
The Living Gita, commentary by Sri Swami Satchidananda
The Power of Myth; Joseph Campbell
Care of the Soul; Thomas More
The Upanishads by Eknath Easwaran

The Yoga Sutras of Patanjali by Sri Swami Satchidananda and
Reflections on the Yoga Sutras by TKV Desikachar

There are beautiful books on the teachings of the Buddha, edited by Jack Kornfield.

Yoga for Body, Breath and Mind; A.G. Mohan
Yoga of Heart; Mark Whitwell
Yoga Body, Buddha Mind; Cyndi Lee
Jivamukti Yoga; Sharon Gannon and David Life
The Anatomy of Hatha Yoga; H. David Coulter
Anatomie pour le movement; Blandine Calais-Germain

Méditer Jour après Jour; Christophe André
The Mudras; Gertrude Hirschi
Perfect Health; (Ayurveda) Deepak Chopra

Favorite Links:
My teachers and others who have inspired me along my path:

Good sites for yoga getaways: