One thing I've noticed recently is the abundance of characters with Migraine in the books I read! I don't mean to select works in which a main character has Migraine; I think it's more likely that Migraine is so very common that it's bound to come up frequently in both fiction and nonfiction.
Ian McEwan's Atonement comes to mind. The mother in the story suffers from very frequent, debilitating Migraine attacks. Think of Virginia Woolf and her struggle with headache as described in her own works, her journals, and in The Hours. I could come up with MANY, many others if I looked at my bookshelf and gave it some thought.
Reading about people who deal with Migraine--whether these people are real or not--helps me immensely. Perhaps above all else is the fact that the author's choice to include a migraineur (or more) shows that he/she is immensely understanding of the disorder. (Especially if the description of the migraineur rings true to a reader who knows the ins and outs of Migraine!) In Atonement, Emily's children know when she's ill just by the way the house is lit, how it feels to walk in the front door. That really resonated with me: I remember running in the front door after school when I was young, realizing too late that I should've been quiet, that I should've heeded the signs. You see, my mom frequently had Migraine attacks (or what I would call Migraine--I am not sure if she was ever diagnosed, but her headaches fit the menstrual migraine description to a T) and I'd know it was that time again by the cool, dark feeling of the house, the curtains in the den drawn as she slept on the couch. Those days were always so sad.
In any case, I encourage you all to share with me (and therefore each other) any books you've read wherein a character deals with Migraine or another chronic pain disease. If you've never read any books with such a character, I encourage you to do so: you'll find a bosom friend who understands you.