tea
 

after a night of drinking i usually have a very queezy feeling in my stomach, like i don't know whether i'm hungry or just sick. i drink a big mug of chamomile tea which helps sooth your stomach and -since it's all herbal- does not contain any caffeine or stuff like that, so it's good for hydration. after that i generally feel much better.
i also used to have a roommate who would take alka-selzer when he had a hangover, he swore it helped. i've never tried it though, basically because i get sick of even thinking about drinking a glass of hot water with powder in it, even when i'm sober/not hungover!:D

but the chamomile tea thing really works!