But wikis are like webpages, or mailinglists (or restaurants, or grouse nests, or...). One either needs a dedicated following, or a high-traffic location.
Like, perhaps, <looking around>, here?
Also, I've seen it said (drat, can't find the nice page) that creating a wiki takes time. One is building a social artifact, rather than merely a technical one. So one creates a site, with some initial interesting content, and advertises it. And adds content, and advertises it. And encourages someone to add something. And advertises it. And so on. It's a cultivation exercise, a community bootstrap exercise, rather than a release-date--ship-it--done one.