Here are some books and audio that have been insightful and enjoyable to read about mindfulness and related topics.

Peace Is Every Step: The Path of Mindfulness in Everyday Life - Thich Nhat Hanh

Full Catastrophe Living: Using the Wisdom of Your Body and Mind to Face Stress, Pain, and Illness - Jon Kabat-Zinn

Still the Mind: An Introduction to Meditation - Alan Watts

Also, these two audio CD collections are helpful:

Out Of Your Mind: The Nature of Consciousness - Alan Watts

Guided Mindfulness Meditation - Jon Kabat-Zinn