I concur about the lack of support at http://www.mediawiki,org/ - are they just overloaded or what?  If they'd open the support wiki to be a little more lenient to contributors like you and I, there's be way more support stuff.  Messy?  Sure.  Helpful?  ONLY if there's tons of information!  Why do they prevent us from helping?  I dunno?!?

Categories in Mediawiki are not automated in any way.  If you already organize your data before you put it into Mediawiki, then you can probably design a category structure within Mediawiki to mimic the real world outside Mediawiki. 

I'm not sure what you want, but I want self building automatic "table of contents" pages (by category) that grow as new pages in the categories they refer to grow.  To do this, I needed to study, explore and copy code from Mediawiki's existing manually creatable lists.  Then I had to find a way to have Mediawiki hold such a new page of code that then refreshes and includes new links to newly created pages in the same category each time the user revisits the main list page I created.  Here's my [ mediawiki:sidebar ] entry showing pages that my Mediawiki now builds for the visitor on demand that contain "categories":

** special:allpages | Article index
** special:allpages/Category: | Category index
** special:allpages/Talk: | Discussion/talk index

I of course had to manually type in something identifying like ...
[ [ category:blah-blah-blah ] ] in at the bottom of the text area for all article pages I then want to be listed in
[ [ special:allpages/Category: | Category index ] ], and for me, it's not the same category for each article.  Some articles also have more than one category - that's okay.

"special:allpages/category" then brings the visitor to a new page showing all categories in the Mediawiki.  Someone can then click on any one of the categories listed on that page to browse down from the general (all categories), to the particular category, then click on a link in the subsequent page to go down to the particular article they are seeking. 

Mediawiki builds each category group page list on demand dynamically after looking up the criteria in the link being clicked on.  That means new pages automatically appear in these lists when someone revisits these list links.  That is what I am after - having Mediawiki do the work of building dynamic and intelligent tables of contents on demand, lists that show newly created pages (so long as each new page is created by someone smart enough to also create a category tag at the bottom of that new page before they save).

I have yet to find a tool to help automate creating categories and marking pages with them - does anyone have any experience with automation here?  All this for me was manual - 400 pages and counting on one Mediawiki installation!  I have another installation that will require manually codifying and categorizing ~4,500 pages during import - wish me luck!

In anyone's Mediawiki installation, we can type into the search box:
[ special:version ] to see what extensions THAT Mediawiki has installed.  These two relate to my category needs and I would probably not have implemented Mediawiki without them:

DynamicPageList2 (version 1.2.1)    based on DynamicPageList, featuring many improvements    IlyaHaykinson, Amgine,Unendlich, Cyril Dangerville,Algorithmix
http://www.mediawiki.org/wiki/Extension:DynamicPageList

Subpage List 2    automatically creates a list of the subpages of a page    Martin Schallnahs, Rob Church
http://www.mediawiki.org/wiki/Extension:SubPageList2

Explore the links above and see if they promise anything for you.  Let us know.


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Here is my TOTAL [ special:version ] print out:

    *  MediaWiki: 1.10.0 http://www.mediawiki.org/
    * PHP: 5.2.2 (apache2handler) http://www.php.net/
    * MySQL: 5.0.41-community-nt http://www.mysql.com/

Extensions

Special pages

LastUserLogin (version 1.0.6)    Displays the last time a user logged in    Justin G. Cramer, Danila Ulyanov, Thomas Klein
http://meta.wikimedia.org/wiki/SpecialLastUserLoginEx

Parser hooks

DynamicPageList2 (version 1.2.1)    based on DynamicPageList, featuring many improvements    IlyaHaykinson, Amgine,Unendlich, Cyril Dangerville,Algorithmix
http://www.mediawiki.org/wiki/Extension:DynamicPageList

Subpage List 2    automaticaly creates a list of the subpages of a page    Martin Schallnahs, Rob Church
http://www.mediawiki.org/wiki/Extension:SubPageList2

Extension functions

wfLastUserLogin, wfUpdateUserTouched, wfDynamicPageList3, wfDynamicPageList2 and efSubpageList
Parser extension tags
<dpl>, <section>, <subpages> and <pre>

Parser function hooks

dpl, int, ns, urlencode, lcfirst, ucfirst, lc, uc, localurl, localurle, fullurl, fullurle, formatnum, grammar, plural, numberofpages, numberofusers, numberofarticles, numberoffiles, numberofadmins, numberofedits, language, padleft, padright, anchorencode, special and defaultsort

Hooks

Hook name    Subscribed by
LanguageGetMagic    wfDynamicPageList3_Magic
LoadAllMessages    wfDynamicPageListSPloadMessages