I was actually thinking of a pianist sight-reading a piece of music, rather than playing it from memory. I find it hard to believe that s(he) has time to consciously process the visual input and decide where to put each finger. A simultaneous translator is another example of the sort of thing I'm thinking of. Driving down an unfamiliar road and thinking about something else entirely whilst your hands and feet automatically turn the wheel/brake and accelerate is another, more mundane, example of the way your brain can directly control your muscles without the participation of your conscious mind.