I'm totally addicted to spearmint chewing gum during the day when i'm in lessons at college, if i don't i just feel i am bound to vomit. Nearly all the time i wake up in the night feeling very nauseous and start chewing a menthol flavoured gum for a few seconds, this eases it immediately.
I've also recently found that listerine mouthwash is a fantastic cure for feeling sick XD