Some personal utils I can share publicly.
Simple, popular easing functions (probably inspired by easings.net). The easing type works as an enum, so it's easy to serialise it and test fast in Unity's inspector.
Enumerators to fulfil common needs while iterating through collections: looping, picking random (but not previously picked) elements.
Copying components from one GameObject to another through the use of reflection.
Calculating the sum of gameObject hierarchy tree renderers bounds.
Simple logging utilities to measure time and GC usage differences in Unity.