I made a new MediaWiki extension, called Data Extension. Its meta page is at
http://meta.wikimedia.org/wiki/Data_Extension and you can see it in action at
http://www.rastko.net/~nikola/ .
The extension enables getting and setting data in articles, with some neat
possible uses. It offers the solution for making sorted lists and an
alternative solution to mass article import. To give an example, in an
article on Paris, you could:
<setdata>
is a=city
population=2144700
is in=France
</setdata>
which would write the data in the database. And then in Template:City you
could have:
Population: {{#data:population}}
which would display it, and the List of cities of France by population could
look like this:
<data condition="is a=city and is in=france">
* [[{{#data:}}]] ({{#data:population}}) {{#sort:{{#data:population}}|desc}}
</data>
It is somewhat redudant with Semantic MediaWiki, because I didn't knew that it
was so developed while writing it. But I think it also offers some things SMW
doesn't have.