I think it'd be useful to be able to create fake galleries which exist in the gallery namespace but cannot contain any photos. These would then be able to act as "categories" so that users could have a list like this:
To berate the obvious: I want to be able to have things in the list which aren't links. Not all categories would usefully have galleries associated with them, and if they did I'd probably want that list automatically generated from a mix of the subcategories in most cases anyway. (Galleries generated by queries is already planned, of course)
An easy (yet not very clean) way to do this would be to just make empty galleries automatically not be links. That way it'd just be a matter of creating a gallery and never putting anything in it. If, later, something manages to fit into the parent category somehow, it's just a matter of uploading a picture to that gallery and it instantly becomes a linked gallery. Sound good?