Rotating vB Category Icons for vB 3.0.3
 

This is what vB category icons are: https://vborg.vbsupport.ru/showthread.php?t=70365

I was wondering if there was a way for them to switch automatically and regularly -- showcasing a different icon/image whenever the user hits refresh or returns to the forumhome.

This should be pretty simple to make, as there are rotating banner hacks available.

The easiest implementation would probably be to separate image names with commas in the admincp, then do an explode(',' on the field and a rand to choose an item from the list. The whole point of having icons for forums, however, is to make them more easy to distinguish; I would think that doing what you're proposing would just be confusing and annoying.