GitHub Audio - Tracks events across GitHub to generate calming work music
EarMaster - Professional software for ear training and practical music theory on Windows and Mac.
Meludia - Listening exercises and to sharpen your ear and music theory skills
GNU Solfege - GNU Solfege is free music education software.
LenMus - LenMus is a free program for learning music.
Perfect Pitch Ear - Piano online for perfect pitch training.