Fretello - Duolingo for learning how to play guitar
Uberchord Guitar - Get better on your guitar. Fast.
Justin Guitar - Over 750 completely free guitar lessons!
Ultimate Guitar Originals - Netflix for guitarists. Fingerstyle. Season 1 announcement 🎸
Guitar Trainer - For guitar, bass, banjo, mandolin, ukulele and cavaquinho
Clapper Game - Hand clapping game meets guitar hero