Fachords - Fachords is an online site that provides many resources that you can use to take your guitar skills to the next level.
Guitarix - Guitarix is a simple Linux Rock Guitar Amplifier for https://alternativeto.
TrueFire - The Best Guitar Lessons Online Fast. Easy. Fun.
GNUitar - GNUitar is guitar effects software that allows you to use your PC as guitar processor.
Gitarrero Beginner - Gitarrero Beginner is a multi-featured, and easy-to-use guitar school developed as a guide to help you learn guitar skills and play them comfortably.
Ampire - State Space Modeled guitar amp/cab/stompbox simulator.