SampleTank - THE MASTER-QUALITY MIDI SOUND MODULE AND GROOVE WORKSTATION FOR THE MOBILE ARTIST.
MilkDrop - 3D audio visualization plugin, compatible with WinAmp plugin API
DSP-Quattro - DSP-Quattro
projectM - projectM is an LGPL'ed reimplementation of Milkdrop under OpenGL.
Audio Cleaning Lab - Looking to clean up your song recordings? Download SOUND FORGE Audio Cleaning Lab, the professional solution for cleaning & restoration with advanced ProAudio technology.
Magic Music Visuals - Fully-customizable and highly responsive visuals for live and recorded audio & MIDI.