I asked for and got a Matias half-keyboard for Christmas. I can type decently on it, but since half the keys require using the shift, and they're randomly distributed (more or less) interms of frequency, I've thought that re-mapping the keys might speed the process up.
Well...it turns out that someone's already done that. It's called a Frog Pad. It's a square keyboard that optimizes for the frequency of symbols. That should inherently make it faster to type on, but since it bears no relationship to the qwerty keyboard, it will be harder to learn.