I've been using an app on my Android called KineStop. It definitely works.

I also recently picked up an EmeTerm wristband - it's basically a mini TENS machine for you wrist. I was super skeptical, but my sister recommended it so I tried it and it absolutely helps with (though doesn't always total eliminate) nausea I get from motion sickness. I'm not entirely sure how it works, but it seems like it may have an accelerometer and use that to decide when (and at what strength/duration?) to send a mild shock.