I am an admin of Crewscut.com, a wiki dedicated to uncovering the landscape of media, culture and technology (so far mostly available in Danish).
Our wiki has been running for two years, beginning with MW 1.3.8. I still consider myself new to MediaWiki, although I'm learning at a staggering rate, following each update with great anticipation. I've also had some experience with HTML, CSS, PHP and MySQL - and have begun experimenting with adding new extensions to our wiki. I hope sometime to find time to write some myself.
Feel free to drop me a note on the talk page or by email. :-)