You won't be seeing Wyatt Earp or Doc Holiday dueling it out with desperados, using guitars as their side arms. I am talking about software.
Multimedia is particularly well suited to teaching instruments.
QuickTime and AVI videos allow students to get up close and personal with the techniques of master performers and instructors. Well designed graphics and animation hold the student's attention, and better user interfaces make navigating and controlling your own instruction easy and immediate. One major advantage of such a program is its potentially unlimited use. In this way these programs become instructor as well as jamming buddy. Unfortunately, these programs can't answer the student's specific questions, improvise, or provide feedback on the student's playing.