I need this because I like to do the equivalent of venting at the top of your lungs over email, but it is very unsatisfying to do when you have to backspace every few words to correct an error. A solution to this problem would be to have the email play when it arrives at its destination in real time, so that I could slow down for emphasis, try to type fast to get across my frustration, and know that every correction etc would be recieved by the receiver and that they would know what I was going through. It would be much more like dancing with your fingers because you could do it in rhythm and slowly get faster or do funny stuff like make jokes and then erase them so they are not in the final serious version.