Radium - Radium is a music editor with a new type of interface.
MilkDrop - 3D audio visualization plugin, compatible with WinAmp plugin API
Keezy Drummer - Make a beat in seconds
projectM - projectM is an LGPL'ed reimplementation of Milkdrop under OpenGL.
BlokDust - Join blocks together to build sounds with this web-based music making app.
Amarok - The Amarok team is proud to announce the immediate availability of the result of 2 years of hard work, the beta release of Amarok 2. 9. This release is marked by improvements, corrections and polishing of nearly all Amarok features.