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.
THIS IS A WORK IN PROGRESS!
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