I like to type my own notes as a talk progresses; reasonably fast typist, helps me tremendously in going over the details of a talk if it had real information content. Valid point about not distracting others; I try and sit to the rear or side of a hall so no-one behind to be visually distracted.
Most impressive typing I've seen during a lecture was a chap throwing all his comprehensive typed points straight into bullet-point slides in real-time, ready for passing on the information to those who couldn't make it to the talk.