Apophysis - Apophysis is a fractal flame editor and renderer for Microsoft Windows.
Magic Music Visuals - Fully-customizable and highly responsive visuals for live and recorded audio & MIDI.
Xaos - XaoS is an interactive fractal zoomer.
MilkDrop - 3D audio visualization plugin, compatible with WinAmp plugin API
Ultra Fractal - Ultra Fractal is a fractal generation and rendering software application.
projectM - projectM is an LGPL'ed reimplementation of Milkdrop under OpenGL.