Sonic-Pi - Live music coding program. http://sonic-pi.net/
Audacity - A free sound recorder and multi-tracker. It is very useful. http://audacityteam.org/
Reaper - It is a free trail for 60 day but it is highly effective as a Digital Audio Workstation, but only $60 dollars for the unlimited version.
Tracktion 4 - Completely free for Windows and Mac. A simple signup and download.