One of my favorite gradient types from the time of Xara was 'Fractal Nosie' and 'Fractal Plasma'. No fine-tuning, but pretty handy for adding quick perturbance, especially when used as a transparency mask.

It’s still there.
Today, VectorStyler app offers a similar gradient type: https://www.vectorstyler.com/documentation/gradients/

We can do something similar using freeform gradient in Ai... but try to scale or rotate control points all at once, I dare you.

Also please take a look at this related request:
Make conical gradient
http://illustrator.uservoice.com/forums/333657/suggestions/36003616