I have been working on a small tool for MediaWiki wikis that produces RSS feeds of members of particular categories. The really different feature of this tool is that, for the publication date of items in the feed, it looks within the page text for a
<time> element. This means that pages can define their own publication date, and subsequent edits to the page will not bump these pages to the top of the RSS feed.
My motivation for this tool was to be able to get a feed out of Wikiversity of, for example, new items in the Wikiversity Journal of Medicine. (This isn't perfectly possible yet, because there's currently no subcategory of Category:Wikiversity Journal of Medicine that just contains articles, and so the feed currently includes pages that it shouldn't.) Or it can be used to get a feed of all recent blog posts (i.e. pages in Category:Blog posts, which I just created).
It also works on other wikis (anything powered by MediaWiki). It's main limitation is that the
<time> element, that records the publication date, needs to be present in the wiki pages in order for the feed to show anything other than the most-recently-modified pages.
The tool homepage can be found here: https://tools.wmflabs.org/mediawiki-feeds
If you have any comments please let me know!