Ability for any product to be placed under several categories.
At the moment a product can only choose 1 category in a dropdown.
What makes sense is that a product can select multiple categories, perhaps not using a dropdown, but a tick box.
Example: A product can fall under category "graphic design" and also "web development" and also "xyz".
But at the moment, this is not possible.
It will make a huge positive difference, quite restrictive as it is right now.