Most of us have experienced pain, but we really didn't know a lot about pain until relatively recently. In Explaining Pain, David Butler and Lorimer Moseley explain that more has been learnt about the physiology of pain in the last ten years than in the previous thousand years.
The book I'm currently working on is mostly devoted to the application of the concepts and theories of injury science and injury biomechanics to facilitate the understanding and study of martial arts techniques and those used in physical violence generally (still working on that description). Naturally, the subject of pain arises throughout the book, however, the final chapter (at this stage) is devoted to pain. It is a fascinating subject; and one that goes to the very heart of martial arts tactics and techniques, and the training thereof.
I 'subscribe' to a particular blog titled: Better Movement: A Brain-Centered Perspective on Performance and Pain. The author posted an interesting blog today which deals with pain and references research: 'More on Pain and Illusions' (http://toddhargrove.wordpress.com/2011/04/19/more-on-pain-and-illusions/).
One of the main themes of this blog is that therapies attempting to treat chronic pain should target the brain for change, not just the body. Some recent studies based around sensory tricks or illusions provide further compelling evidence in support of this idea.I think you'll find the blog interesting. Believe me, there is a lot more to add to the 'pain story'.