Changing category order in category menu bar, not in sidebar cat. list

So far, I have not found a way to re-order the categories in the category menu bar. It's possible in the sidebars, but I don't even care about having the categories there. I have too much other content there already.

Has anyone found a way to do this? It seems that WP keeps the categories in the order in which they were first created. I want them in order of importance and/or popularity, decided by me, not the system.