gatoade/powerade or something like that works for me. don't usually get hangovers. but when i do they are bad. there are some things that you can take before drinking or bed but i haven't tried them. i'll bet rob has some good ideas 
I always have good ideas...
The surefire hangover cure is two fold:
1. Never ever mix your poisons! That means if you're on beer... stick to beer! If you're on liquor... stick with one type of liquor! That means rum and rum shots are ok... but don't throw vodka into the mix...
2. (most of you will not believe this is coming out of my mouth) Moderation and hydration!!! Have a glass of water every two or three drinks throughout the evening...
However, should you decide to mix up the chemicals or overindulge, try the following (however, there is no known cure for a hangover)...
1. Drink a LARGE glass or two of water before bed... Mix some lemon juice and honey into at least one of the glasses.
2. Avoid taking any type of pain killer, i.e., aspirin, Tylenol, Motrin, Aleve, etc, that night (or even the next morning if you drank a lot)... there has been lots of research done and the findings are that mixing these type of pain killers with alcohol can cause liver damage. I've had two friends that typically took pain killers before going to bed after a night of hard drinking and both had reduced liver function (one was down to 25%, the other 45%).
3. While the hair of the dog is popular, it really does more damage than good... it will get rid of the hangover, but you will be drunk again.
4. The next morning, you can take aspirin to help alleviate the pain, and drink a lot of water to rehydrate.
Trust me... I'm a professional drinker from way back!