Plane9 - Plane9 is a revolutionary 3d visualizer where you never have to settle for just one view ever again.
Wallpaper Engine - Wallpaper Engine enables you to use live wallpapers on your Windows desktop.
MilkDrop - 3D audio visualization plugin, compatible with WinAmp plugin API
ScreenPlay - Open-source and cross-platform Wallpaper, Widgets and AppDrawer app.
Magic Music Visuals - Fully-customizable and highly responsive visuals for live and recorded audio & MIDI.
Lively Wallpaper - What is it? Lively is a Free and Open-Source Software (FOSS) for animated desktop wallpapers.