Algorithm Visualizer - Write down your algorithm to be visualized
MilkDrop - 3D audio visualization plugin, compatible with WinAmp plugin API
The Algorithm Design Manual - Learn about designing and analyzing algorithms
projectM - projectM is an LGPL'ed reimplementation of Milkdrop under OpenGL.
State.of.dev - Visualizing the current state of development
Magic Music Visuals - Fully-customizable and highly responsive visuals for live and recorded audio & MIDI.