Long ago I read somebody's theory (Bruce Chawin's, maybe?) that the reason so many poisons cause dizziness is that the inner ear is an extremely delicate mechanism and so is easily thrown off such that visual perception and positional sense no longer matches what the ear is saying. The theory further suggests that the brain is evolved to work that backwards: if the body is sufficiently dizzy, it has been poisoned, so it had better empty the stomach.
For me the trick is to keep motion perception in sync with the inner ear. So if I'm on a boat, I'll aim my head in the direction we're heading and think of myself as moving with the boat. Same thing with cars: on a bumpy or swervy taxi ride I'll look straight ahead and think of myself as moving with the car.
It sounds ridiculous, but it works well for me. Living in SF, I've had many chances to try it out.