Qsynth - Qsynth is a simple Qt4 application wrapper for the ...
MilkyTracker - MilkyTracker is an open source, multi-platform music application for creating .MOD and .
VirtualMIDISynth - VirtualMIDISynth is a software MIDI synthesizer implemented as a Windows multimedia user driver...
OpenMPT - OpenMPT is a popular tracker software for Windows.
ZynAddSubFX - ZynAddSubFX is an open source software synthesizer for Linux, Mac OS X and Microsoft Windows.
FamiStudio - FamiStudio is very simple music editor for the Nintendo Entertainment System or Famicom. It is designed to be easier to use than FamiTracker, but its feature set is also much more limited.