Bosca Ceoil - A free, easy to use tool for creating music.
MilkyTracker - MilkyTracker is an open source, multi-platform music application for creating .MOD and .
Zynewave Podium - Podium is a modern digital audio workstation (DAW) for Windows.
OpenMPT - OpenMPT is a popular tracker software for Windows.
Renoise - Renoise is a digital audio workstation.
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.