MilkDrop - 3D audio visualization plugin, compatible with WinAmp plugin API
Tilt Brush - Paint in spaces around you with Virtual Reality
projectM - projectM is an LGPL'ed reimplementation of Milkdrop under OpenGL.
Oculus Medium - Sculpt, model and paint in virtual reality on a 3D canvas.
Magic Music Visuals - Fully-customizable and highly responsive visuals for live and recorded audio & MIDI.
MasterpieceVR - Powerful VR sculpting & painting tool