RapidComposer - MusicDevelopments RapidComposer: Music Prototyping and Automated Composition Software
Guitarix - Guitarix is a simple Linux Rock Guitar Amplifier for https://alternativeto.
Captain Chords - Write chord progressions in your favorite DAW
GNUitar - GNUitar is guitar effects software that allows you to use your PC as guitar processor.
Odesi - ODESI is a music sketchpad that exports your projects to Audio and MIDI.
Ampire - State Space Modeled guitar amp/cab/stompbox simulator.