This is the top category of WikiLists' actual content: the lists of all kinds.
Currently, the categorization is just as its beginning, see Forum:Categorization for details.
A full, alphabetically sorted list of existing categories can be found at Special:Categories. A lot of lists are still uncategorized.
Ideally, every list should be in at least one category; many will fit well into two (eg. location and subject-matter), or more.
To add a new category, just add
[[Category:Categoryname]] to the list or existing category page (after checking whether any existing category is suitable).