MilkyTracker - MilkyTracker is an open source, multi-platform music application for creating .MOD and .
SoundGrail - SoundGrail Music App designed for pianists, guitarists, and DJs.
OpenMPT - OpenMPT is a popular tracker software for Windows.
keezy - A colorful soundboard. Play with music.
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.
G-Stomper Studio - G-Stomper Studio is a feature-packed, mobile music production tool.