Might want to check on Dionysis, Greek god of Wine and Revelry. Occording to Deities and Demigods, his portfolio includes Mirth, Madness, Wine, Fertility and Theatre.
Domains of Chaos, Destruction and Madness.
The best I can do out of the FRCS is Sharess, who is the Godess of Festhalls. Domains of Chaos, Charm, Good, Travel and Trickery.
No actual drinking gods, not even among the dwarves.
The Discworld had (for a short time I think) a oh-god of hangovers (oh-god because he usually was invoked by people with the words "oh, god")
For FRCS: Ed Greenwood has a character appearing in some of his books: Rathan, the fat priest of Tymora. He always eats and drinks a lot, and thats because he wants to invoke his luck (a goddess of good luck is a nice patron for drinkers - as we all know: luck is with children and drunken ones)
2nd Edition D&D Netbook of Alcohol had 2 gods of alcohol; one was of wine and good (had Valkryies as servants) and the other of Liquor and evil (had, I think, evil Clydesdales). Worth checking out...