If you do not know about FX Composer 2 yet and have not seen it before, check it out if you do any shader development at all. I was a big fan of FX Composer 1 and previewed FX Composer 2 kinda early and used it a bit in the Arena Wars Reloaded OpenGL Shader development.
The best features are full Collada support and full DirectX, OpenGL, FX (hlsl), CG and CGFx support and the nice UI and cool new features and toolboxes. The beta 3 version was released yesterday (first public version) and the final version will probably be available soon.
http://developer.nvidia.com/object/fx_composer_home.html#downloads
Mental Mill is also a part of the FX Composer 2 beta 3 installation. It is a really cool tool for artists, who do not want to hand-code shaders themselfes. Instead you can drag and drop components onto the workspace and connect them visually to create a shader. Really cool stuff, one of my artists is really a big fan of shader creation this way. I haven't used it much myself yet, I always end up finetuning the shaders myself.
Mental Mill:
