Audacity - Audacity is a free and open-source audio production software suite that includes a surprising array of editing tools and recording systems.

keezy - A colorful soundboard. Play with music.

GarageBand - GarageBand is a fully equipped music creation studio for Mac

Figure - Propellerhead creates world-class software products and services that inspire music makers and provide the foundation for a worldwide creative musical community.

SunVox - SunVox is a small, fast and powerful modular synthesizer with pattern based sequencer (tracker).

Splice - Music creation, collaboration, and sharing made simple.