Margarita:

I've been using the "water cure" for hangovers for years, ever since I heard about it, and it has never let me down. I've heard it's something about the alcohol dehydrating your brain (real neat stuff to do to your brain, isn't it?) that causes your head to hurt and the water replenishes the lost fluids, although I can't verify that. In any event it works. The only drawbacks: you may have to stagger to the bathroom to relieve yourself in the small hours of the morning, and you have to be at least not so drunk as to forget to drink a lot of water right before you go to bed.....