SunVox - SunVox is a small, fast and powerful modular synthesizer with pattern based sequencer (tracker).
Loopy Pro - Loopy, the sophisticated, tactile live looper app that reinvents iPhone and iPad music making.
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.
Repetito - Repetito: the multichannel looper software for live performance on the PC.
MOTU Digital Performer - Get inspired, then refine your mix — all in a singular workflow.
Group the Loop - Live Looping with usefull GUI, Verse/Chorus layer system, drummer, effects, etc...