MilkDrop - 3D audio visualization plugin, compatible with WinAmp plugin API
MadMapper - The Mapping Software
Magic Music Visuals - Fully-customizable and highly responsive visuals for live and recorded audio & MIDI.
Resolume - Resolume is an application for live video performances.
Plane9 - Plane9 is a revolutionary 3d visualizer where you never have to settle for just one view ever again.
Linux Show Player - Sound player designed for stage productions