Here are some books and other material that I recommend.

Asana (Physical aspect of yoga):

• Hatha Yoga - Godfrey Devereux
• Light on Yoga - Iyengar
• The Heart of Yoga - T.K.V. Desikachar
• The Breathing Book - Donna Fahri

Inspirational:

• Autobiography of a Yogi - Paramhansa Yogananda
• Cave in the Snow - Vicki Mackenzie
• Siddharta - Herman Hesse
• The Alchemist - Paul Coelho
• The Eleventh Hour - Pandit Rajmani Tigunait

Meditation

• Breath by Breath - Larry Rosenberg
  
• Bringing Yoga to life - Donna Fahri
  
• Meditation - Advice To Beginners - Bokar Rinpoche
  

Philosophy:

• Be As You Are: Teachings of Sri Ramana Maharshi - David Godman
• The Living Gita - Swami Satchitananda
• The Shambhala Guide to Yoga - Georg Feuerstein
  
• The Tibetan Book of Living and Dying - Sogyal Rinpoche
• The Yoga Sutras - Patanjali
  

Pregnancy

• Yoga for Pregnancy - Wendy Teasdill
  
• Preparing for Birth with Yoga - Janet Balaskas
  
• Yoga for Pregnancy DVD - Shiva Rea
  

Sounds

• Sound awareness (mantras) - Chloe Goodchild
  
• Embrace (mantras) - Deva Premal
  
• Shakti Rhythms (practice asanas to) - Shiva Rea
  

Women

• Women's bodies, women's wisdom - Christiane Northrup