High exersion rides in hot, sticky weather often bring on post ride migraines for me.
I find a little Vitamin I pre-ride (um, that's Ibuprofen), an electrolyte drink in the waterbottles, and a high-protein drink (I've been doing a 10 ounce gulp of Accelerade) post ride help.
Other than that, a lot of food and drink (and a nap if I can swing it) help me get on the right track again.