I've mentioned my RSI a few times now. In 2008 and 2009, NaNoWriMo left me in agony for the month of December. Last year I was able to continue with no problem, despite logging my highest word count ever. What made the difference? Dragon NaturallySpeaking.
For those unfamiliar with the name, Dragon is speech recognition software. Instead of using the keyboard to input the story, I talk into a microphone. Dragon transcribes my words onto the screen as I watch, with remarkable accuracy. It took about a week to learn to think out loud--writing is oftentimes a very kinetic process, and you do lose that with this software.
Since November, I've been able to use Dragon for another important part of the writing process. I've blogged a few times about revisions and my multiple, color coded, hand-written drafts. Once I go over a chapter in both purple and pink ink, it's often so different from the original that typing the edits would be too much for my wrist. Instead, I dictate the new chapter back into the computer.
Here's the other benefit I gain from this: I get to hear my story out loud. Words sound different when spoken. It's a simple fact, but one we often don't really think of. Dialogue that looks perfectly natural on the page may sound trite or overly sentimental. By giving myself a chance to listen to my story, I catch places that need a little extra help.
Speech recognition software isn't for everyone, but I do encourage you to read your story out loud. Ask a friend to listen with you--you already know when your story is supposed to be funny or sentimental. Gauge their reactions and adjust your story accordingly.
Good luck!