Radium - Radium is a music editor with a new type of interface.
SunVox - SunVox is a small, fast and powerful modular synthesizer with pattern based sequencer (tracker).
Keezy Drummer - Make a beat in seconds
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.
BlokDust - Join blocks together to build sounds with this web-based music making app.
MOTU Digital Performer - Get inspired, then refine your mix — all in a singular workflow.