Anvil Studio - Free Windows multi-track MIDI/Audio recording & editing, VST Effects & Instruments, automation. Options for Sheet Music printing, music theory, ear training.
Jokosher - Jokosher is a simple and powerful multi-track studio.
LMMS - Make music with a free, cross-platform tool
Fission - Edit audio in minutes, not hours.
Cakewalk - The next generation of SONAR, the world's finest and most powerful DAW - now FREE.
MusicBoard - Mb Launchpad is the first Linux launchpad.