Put __HIDDENCAT__ on the category page to hide that category from the list at the bottom of the article pages. This feature is intended to reduce the clutter from maintenance categories like [[Category:Articles with unsourced statements since December 2007]].
I was just looking at using this feature on commons, where license categories clutter the category lists of image pages considerably (and provide redundant information, as we already have template for the licenses).
I tagged a few cats with __HIDDENCAT__, but unfortunately, while useful for the image pages, it screws up category tree navigation. Numerous licenses have finer grained subcategories (such as i.e. PD-old).
How about disabling the category hiding for the category namespace?