Guitarix - Guitarix is a simple Linux Rock Guitar Amplifier for https://alternativeto.
EarMaster - Professional software for ear training and practical music theory on Windows and Mac.
TH-U - World class guitar amps and effects for PC and Mac
Meludia - Listening exercises and to sharpen your ear and music theory skills
Ampire - State Space Modeled guitar amp/cab/stompbox simulator.
LenMus - LenMus is a free program for learning music.