Lumonix has released ShaderFX Free to users, allowing real-time editing of shaders inside 3DS Max.  It covers shader models 1.1 to 3.0, results can be viewed directly in the 3DSMax Viewport, and you can export your results in HLSL or CGFX formats for use in other tools or applications.

With Shader FX, artists no longer depend on external applications to get the effects they want. Finally artists have a tool that enables them to create stunning real-time shaders quickly and easily, and gives full control over the appearance of their real-time models.

via Lumonix.