GarageBand - GarageBand is a fully equipped music creation studio for Mac
Qsynth - Qsynth is a simple Qt4 application wrapper for the ...
Ohm Studio - Ohm Studio is the first real-time collaborative digital audio workstation.
VirtualMIDISynth - VirtualMIDISynth is a software MIDI synthesizer implemented as a Windows multimedia user driver...
FL Studio - Image-Line's FL Studio, now on it's 12th version, is a well-known music production suite and the most popular beat processor on the market, due no doubt to its longevity. Read more about FL Studio.
ZynAddSubFX - ZynAddSubFX is an open source software synthesizer for Linux, Mac OS X and Microsoft Windows.