Audion (version 0.1.0)
Audion thumbnail image
(click above for full image)

Audion is an application for creating your own instrument and effect plugins.
We've divided our road map into three general phases:

Phase 1: being able to patch together preexisting modules into a working interface-less audio plugin.
Phase 2: creating a graphic interface for this plugin and wiring up the controls to the modules
Phase 3: going beyond just patching, and program new modules in a language we are calling "Fast".

We are currently in phase one; this screenshot will show you the direction we are heading.
For 32-bit Windows, you need to have .NET 4.0 installed to run it.
Open source, written in C# and C++

download Audion
source code is available here