I don’t even own a guitar, but ActionTab caught my eye:
ActionTab is a new way of teaching guitar at a global level — via the internet. The actiontab tutoring system utilizes Macromedia Flash Player software in order to provide site users with an audio-visual method of learning guitar. Although complex in design and application, the end product is relatively simple for people to use and enjoy. The simplest description of ActionTab’s core concept is that it is ‘one step short’ of sitting in front of a guitar teacher and watching/listening as they show you how to play pieces of music on the guitar. The ActionTab tutor shows the fretboard of the guitar (see diagram below), and also each appropriate finger movement precisely — synchronized along with the recorded music. Each finger placement and action is denoted by simple, colour-coded dots. There is simply no easier way to learn new guitar songs.