A better keyboard
Make a keyboard that detects slight movements in fingers, so all you have to do is twitch, basically. Make an impulse in the direction that your finger would normally have to move to press a given key. Perhaps use technology related to that used in a pointing stick, to detect twitches. (let it also detect down-pressure)
Of course this alone couldn't account for all the keys on a keyboard. Some keys you would just have to move your finger for.
Who knows how fast people could type with this..