that depends what you would want to do exactly, but if you want to add a global parent category on top others, that could be done by sql i guess.. but permalinks would be screwed i suppose : P

You could do it in phpmyadmin.
But that is not easy, nor recommended..
BUt it is possible

I would not want to add a top category, but rather a child category like "automotive" or "family visits."

I think the easist method is to just add the category as you go...
You would be surprised how quick you will will be able to knock over a lot of posts just doing a few at a time ( unless you have 100's of posts )

Oh, I have done it. It took me a few hours of "a few at a time" to do like 50 posts (when I created some child categories). That was easier, though, since I could at least narrow it down to the posts marked PETS, and then add the necessary pet name after that. But to sort through 4-5 years of posts? I would love a much easier/quicker way.

i agree there's gotta be more checkboxes around the admin area, to moderate huge content.. (checkboxes near comments, posts, etc. etc.. for massive deleting i.e)

Exactly!

Maybe for the next upgrade of b2evolution? Pretty pretty please? :D