I found the svn repository for MediaWiki extensions:

http://svn.wikimedia.org/svnroot/mediawiki/trunk/extensions

There are a lot of extensions in there. Not sure if adding it as an external on my own repository was a good idea or not. Let’s see how that goes.

At a glance I found a few interesting extensions. I bumped into them while searching for a NoTitle extension, which I couldn’t find. There was StalkerLog, which logs user logins/logouts; and WhoIsWatching, which displays who is watching particular pages.