I agree with the above posters on the Wristband method of alleviating motion sickness. Whilst I have not suffered myself, when I was an instructor I had a female student that suffered very badly. Using the bands cured her motion sickness almost entirely.
Also, I think there is a point that often when someone suffers from extreme motion sickness, their blood sugar levels are low, such as if they haven't really eaten anything. Typical scenario is someone who knows they feel sick when they fly so they don't eat for the risk of bringing up a huge meal. From my experience, I have noticed that if someone regularly has problems, if they can be persuaded to eat prior to flying (and I don't suggest a 3 course meal, just a light meal- sensibly balanced) then they seem to suffer less motion sickness.
However, the bands definitely work as long as they are in the right position. They also helped my wife when she was suffering from pregnancy-related nausea. If she took them off, the nausea returned within 30 minutes!