I really like the scattering media, and the mathematical figures you can do with it, such as 3D Julia fractals and noise patters to model really rough "stony" s

I really like the scattering media, and the mathematical figures you can do with it, such as 3D Julia fractals and noise patters to model really rough "stony" surfaces that aren't just bump maps. On top of that I don't think I've found a better way to generate various patterns and textures, even for simple 2D work. It's just such a versatile set of tools you almost wouldn't believe it's free! And the fact that it's entirely scripted (unless wysiwyg megapov etc) just makes it better IMHO. It's a scripting-first modelling language, and I really, really like that. With that comes things such as inverse kinematics and gravity (for animations) without having to learn specialized GUIs or buy expensive software.