Wikimedia Bugzilla is closed!

I would like a way to list articles that belong to several specific categories.
I believe this would make the wiki a lot more powerful, and suited to take on
more complex tasks.

Subcategories are nice, but sometimes your categorisation schemes are orthogonal
and it doesn't make sense to just pick one to be on top in a hierarchy.  But
there is still much value in being able to use them togehter. Consider a company
intranet that includes these categories:

* Person
* Project
* Department
* Department:Admin
* Department:Sales
* Department:Dev

Wouldn't it be great to be able to list all the projects in Sales, or all the
persons in Admin, without sacrificing the ability to list either all projects,
or all persons, or all pages under Sales, as the subcategory would?

The information is already there, only the filter is issing.  A special kind of
category page might be the simplest way, but the most useful would be a plugin
for inling the results o such a query.

The idea could be extended to arbitrary boolean expressions of categories, but
it's the AND that really adds lots of everyday-useful power in one swoop.