Transcribe - An online app that reduces the pain of converting audio & video to text. Saves thousands of hours every month for journalists, lawyers, students and professional transcriptionists all over the world, including researchers in Antarctica.
UltimateGuitar.com - Learn how to play your favourite songs on guitar or ukulele
Tune Transcriber - Learn and transcribe music for free from your web browser (no install needed).
ChordU - Extracts chords from any song, integrated YouTube.
Guitaa.com - Turn ANY song into chords, play along with interactive chords and diagram, transpose, loop, tempo control.
Guitar Dashboard - Open-source interactive music theory for guitarists.