Audacity - Audacity is a free and open-source audio production software suite that includes a surprising array of editing tools and recording systems.
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.
G-Stomper Studio - G-Stomper Studio is a feature-packed, mobile music production tool.
Reaper - Reaper is a focused digital audio workstation (DAW) developed by Cockos. In the creation of the software, the digital audio technology company intended to make audio editing accessible to the masses.
Caustic - Caustic is a music creation tool inspired by rack-mount synthesizers / samplers rigs.
Ardour - Record, edit, and mix on Linux, Mac OS X, and Windows.