SoundGrail - SoundGrail Music App designed for pianists, guitarists, and DJs.
Fretello - Duolingo for learning how to play guitar
keezy - A colorful soundboard. Play with music.
Justin Guitar - Over 750 completely free guitar lessons!
Figure - Propellerhead creates world-class software products and services that inspire music makers and provide the foundation for a worldwide creative musical community.
Uberchord Guitar - Get better on your guitar. Fast.