I've been using the Chaser anti-hangover pills for a while. I recently switched to the less expensive Sobr'K Hangover Stoppers.
http://www.hangoverstopper.com/products/
Both brands of pills are just activated carbon (charcoal). I usually pop two when I start drinking and then a few more over the night.
The few times I've forgotten to bring/take the pills I've had a miserable hangover. With the charcoal pills I just feel a bit tired.
Your crap will be black the next day but that's all part of the fun.
