His
"Extremely Quick and Simple Introduction to the Vi Text
editor," and
his introductions to the elvis and vim extensions to vi. The latter are much better than
ordinary vi (and far, far better than pico). X11 mouse capability;
subwindows (even on nongraphics terminals); infinite undo; paragraph
formatting and so on.
Dr. Matloff's introduction to the mutt e-mail
utility. Don't use pine! It was designed for people who are
afraid of computers, not for computer experts.