You could have downloaded projectM 3.1.12 for Mac from our software library for free. The software lies within Audio & Video Tools, more precisely Music Production. This free Mac application was originally created by Mischa Spiegelmock.
From the developer:
projectM is an awesome music visualizer. There is nothing better in the world of Mac. projectM's greatness comes from the hard work of the community. Users like you can create presets that connect music with incredible visuals. projectM is an LGPL'ed reimplementation of Milkdrop under OpenGL. All projectM requires is a video card with 3D acceleration and your favorite music.
You may want to check out more software for Mac, such as M-Audio Key Rig or Speak, which might be related to projectM.