June (NYC, USA) on 11/30/2008:
When I was in college years ago, I took a class on the Linklater Voice method, which was recommended for actors and public speakers. I remember being told that one of the exercises we used to warm up at the beginning of class was excellent at reducing or eliminating TMJ. This particular warm-up exercise consisted of grabbing a good hold on your chin between your thumb and pointing finger and vibrating it (shaking it very quickly with tiny movements) while making an "AHHHHH" sound. Then you'd continue with the vibration and make a very deep sighing noise going up and down the scale (picture a sound wave curve). You might want to do this in a sound proof room because people may wonder what the heck you are up to -- very silly sounds!
I have used the technique successfully over the years to treat my TMJ when it popped up. I spend 5-10 minuts making sounds and vibrating my jaw. I also move my jaw from side to side while making that AHhhh sound.
Magnesium is a potent stress reducer, so you might consider taking that too.
P.S. I haven't checked, but maybe there are some videos on YouTube on the Linklater voice method to give you an idea.
P.P.S Babies sometimes make a very similar sound to the vibration I described above!