Several months ago, I proposed some extra-informations for categories. The data I proposed was to help making an RSS feed with the last articles added into a category. The data could be a short description put inside the category tag like [[Category:XXXXX | SortTag | The XXXXX is the qsdj o fjqipsdf psqiodf.]] An other idea was to be able to read this tag in a page for last added articles, to avoid manualy updating lots of lists.
I did not have the time to work on sthg like it, but, even if it's not really related to Bill's question, I still think it would be one of the numerous good functionalities to add to mediawiki :)
Plyd