Just chatted with Clixyz and he brought up an old wish:
When we select one or more objects it would be great to have some kind of visual indication on the layers in the Layer Panel. When working on large files (at least when made by others).
Illustrator does this nicely by adding a circle around the “select objects on layer icon”.
Rhino could use a yellow triangle in a corner, or a box around the layer color icon, or a new indication all together.