I also spend a lot of time writing ideas and doing calculations in notebooks - pen and paper. Typing math is a lot slower than writing it, because there are all sorts of weird symbols, and I always using weird mixtures of equations and diagrams. It would be nice to computerize this, but drawing with a stylus feels clumsy, and converting hand-written equations into LaTeX hasn't been automated yet. So here again, there's a lot of room for improvement.