VertexDSP has released FaderWorks for Mac OS X in VST and Audio Unit formats; the Windows version was released before Christmas.

FaderWorks is an audio plug-in for intelligent gain adjustment. The main idea behind FaderWorks is to provide an additional layer of control and flexibility to a mixing environment.

At its simplest, FaderWorks can be placed anywhere in the effect chain of an audio track. This allows you to specifically control the volume behind or before other audio plug-ins. The main idea behind FaderWorks comes to life when two or more instances are opened. These instances can be connected logically to each other. Using FaderWorks in this way, it is possible to manage complex mix setups with just one volume fader.

FaderWorks costs $65 but until the end of January 2007 it can be purchased for an introductory price of $45 (discount of 30%). A demo version is available.