Learn about the parts of the guitar, types of guitars, listen to sound clips of other interesting string instruments, learn to read guitar melodies with tablature (link included) and basic guitar chords. Click on titles of the music to listen to the songs being played on a guitar and use an online guitar tuner.
There are also links to videos of famous guitar players of several styles and time periods: Andres Segovia, Les Paul, Van Halen, Joan Jett and B.B. King.