I have been working on wiki’s for a number of years already, not the wikipedia one as they have way to strict rules if you ask me and everything I added on there was almost immediately removed again, so not going to edit anything on there anymore. Instead I have been working on a wiki for a videogame I play(ed) over at www.entropiaplanets.com. The wiki was there when I first arrived on the site, but there was basically nobody running it. like now, I had an interest in gathering info and data, so the step was pretty easy to dig into that wiki and add data to it. First this was with the basic wiki software but after another guy (Eric) joined in on the quest to collect data we changed it to Semantic Mediawiki (SMW) which gave us the power to do very cool things like displaying data not only in tables, but also in graphs and even on maps. Over time the work on that wiki stopped due to loss of interest in the game and other stuff to do, but the interest in the wiki software stayed.
I ended up helping a few people with their wiki. People posting some problem or issue on a mediawiki developer page on Facebook which I am part of. So far it has been the Lost Media Wiki that needed some help with the way the wiki looked and I was able to help him a bit. This wiki is all about lost media, meaning videos, music, games that we know are made, but seemed to be lost for some reason.
Later it was the British India Wiki a wiki about British Indian coins. This wiki was being made with standard wiki software,. but the kind of data that was added was perfect for SMW, so I suggested this and made a small example wiki to show what was possible. A few hours later the wiki was changed to one that had SMW and I explained a few things about how to work with it and how to add things. Now, about a week later that wiki has grown pretty quick and the guy building it seems to like SMW and is pretty good with it already.