I recommend "Breaking the Headache Cycle" by Ian Livingstone, MD, and Donna Novak, RN. Livingstone is a neurologist at the Princeton Headache Clinic. While the book is very technical at times, it's not hard to comprehend. The authors discuss the neurological basis of migraine, and they provide suggestions to help identify triggers and cope with pain, etc.
http://www.amazon.com/Breaking-Headache-Cycle-Preventing-Recurring/dp/0805072217