This is a bit of a technical one! I built a node iterator/looper for Nuke (using Python).
It acts like a solver in Houdini - simply feedback-looping a set of nodes over and over again. With some controls for variations per iteration, easy scrolling through iterations, and automatic relinking.
This allows for generating fractals in Nuke, or drawing reaction diffusion.
For an in-depth explanation of how this works and how you can try it yourself, see my website:
All following images are generated entirely in Nuke!