SunVox - SunVox is a small, fast and powerful modular synthesizer with pattern based sequencer (tracker).
SoundGrail - SoundGrail Music App designed for pianists, guitarists, and DJs.
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.
keezy - A colorful soundboard. Play with music.
MOTU Digital Performer - Get inspired, then refine your mix — all in a singular workflow.
Splice - Music creation, collaboration, and sharing made simple.