I worked with a developer that had RSI. He used exercise, both grip strength and stretching / yoga to deal with it. He also switched to using a Dvorak keyboard.

I worked with a developer that had RSI. He used exercise, both grip strength and stretching / yoga to deal with it. He also switched to using a Dvorak keyboard. His situation did get better, but his recovery couldn't be definitively attributed to a specific change he made. We had an interesting discussion around the theory and the math behind the Dvorak construction of the layout. The gist of it is that there are some natural and unnatural hand movements made while typing. The standard keyboard was constructed to statistically minimize typing letters that would cause the typewriter arms from getting tangled, from overlapping / locking. The Dvorak keyboard was optimized to place the most commonly typed letters in places that your hand could comfortably get to (reducing the frequency of stressful motions on the hand). However, the scientific evidence wasn't conclusive. Good luck.