My suggestions were going to be:
B6 and water beforehand.
Not mixing your drinks during.
More water after.
Then sex and/or bananas the next morning.

But they've all been mentioned already (maybe not in that combination). Ah well - it works for me.

Cheers
- Chicky
(who's a bit out of the hangover habit what with several consecutive years of being pregnant with or breastfeeding my three babes - but I'm finally finished with all that now - yeehah!)