Input Solutions for Repetitive Stress Victims?
Keyboards with a built in trackpoint (the little eraser nub) are available from several companies, including IBM and Unicomp http://www.pckeyboard.com/
The only motion required from a normal home-row typing position is to move your right or left index finger over about 2cm, and the thumbs don't have to be moved, as they naturally rest on the left and right mouse buttons, respectively.
This is very low stress, and the keyboards tend to be good quality. I use this with my IBM laptop for usually upwards of 12 hours a day (IRCaholic), for many years, and have no hand problems.