Another tertiary effect of aperture is in the creation of starbursts. Some lenses are more susceptible than others to this effect, but the general idea is that one can get a pleasing (or not) starburst at smaller apertures. Like this:
Some photographers use this tertiary effect. There are filters available that create starbursts at any aperture.
One could include lens flare in this discussion, but it is not really related to the legs of the exposure triangle. It has a lot more to do with the types of coatings are used in the manufacture of the lens elements.