SoundGrail - SoundGrail Music App designed for pianists, guitarists, and DJs.
Bosca Ceoil - A free, easy to use tool for creating music.
keezy - A colorful soundboard. Play with music.
Zynewave Podium - Podium is a modern digital audio workstation (DAW) for Windows.
Splice - Music creation, collaboration, and sharing made simple.
Renoise - Renoise is a digital audio workstation.