Guitaroid - Listen to Guitaroid | SoundCloud is an audio platform that lets you listen to what you love and share the sounds you create.
UltimateGuitar.com - Learn how to play your favourite songs on guitar or ukulele
Metronomus - Powerful and beautiful online metronome
ChordU - Extracts chords from any song, integrated YouTube.
Guitar Dashboard - Open-source interactive music theory for guitarists.
Guitaa.com - Turn ANY song into chords, play along with interactive chords and diagram, transpose, loop, tempo control.