for some reason I never tried smoking after a hangover, which is weird considering how much of a pothead I used to be.  but I can personally attest, weed has AMAZING anti-nausea properties.  last new years eve I got stuck at home with the stomach virus from the depths of hell.  I was throwing up for 6 hours, each time completely draining my stomach, and then a 5 minute break in between.  i was close to tears at one point, because I couldnt breath and thought I was gonna die.  well, I mustered the energy to smoke a gb bowl, and I felt perfectly fine for about an hour and a half.  then the misery resumed.
my freshman year hangover cure involved mucha agua and a special college recipe of mine...macaroni and bacon.  you can make both in a microwave, and its fucking amazing.  its an orgasm for your mouth and if you drink plenty of water with it, you will wake up feeling fine in the morning after that first cup of coffee.