projectM - projectM is an LGPL'ed reimplementation of Milkdrop under OpenGL.
QLab - QLab, Live show control for Mac OS X.
Magic Music Visuals - Fully-customizable and highly responsive visuals for live and recorded audio & MIDI.
Cue Player - Cue Player software for theater sound and lighting
Kauna - Kauna is a music visualizer. Kauna renders any sound reproduction in system.
MadMapper - The Mapping Software