Short version: Wetpaint might be one to watch.
Long version: TechCrunch's Michael Arrington has alerted us to a dark horse candidate in the race to dominate the land of wikis. It's Wetpaint, a Seattle-based service we haven't heard a whole lot from lately. The reason, Arrington says, is that it's positioning itself to be a player in niche social networks, not just mini-Wikipedias.
The easy-to-create wiki service pulled in 3 million page views in March, according to ComScore numbers, compared with 3.8 million for Ning, the well-funded social-network creator helmed by Marc Andreessen. Wetpaint also claims 900,000 wikis have been created, far more than the 263,000 that Ning counts (though who knows how many of those are legitimate and/or active). While Ning's way ahead in traffic, a few months ago Wetpaint released a set of features to ramp up social-networking activity on the site, with friends lists, news feeds, member profiles, and Yelp-style "compliments" now in the mix.
There are also 70 "sponsored" Wetpaint wikis, like the fan wikis created by cable network Showtime for each of its programs.