I lost the wiki on this site due to hackers. I didn’t have a recent backup so I am trying to recover as much as possible from Google cache. The wiki wasn’t a wiki anymore anyway: i needed to close it for public editing due to spam bots.
The best solution I have seen for fighting this kind of automated spam is a small Turing test. Ingo Hinterding has good experiences with it and it seems to protect is comments quite well. It may also be easier to implement that captchas. Here is a german article about the issue. It contains a quote by Stephan Mosel:
Open wikis are so 2004!
Well, I’d add that closed wikis aren’t anything beyond 2004 as well. The open editing of wiki pages is a key for success of wiki sites. I don’t want to contact the site maintainer or subscribe to an account when coming across a wiki page that I feel needs some refinement.