I've not written my own wiki or blog system, and not thought about this problem at all. Given that, what if a form of "email authentication" was used to approve wiki edits and blog comments? (I think I've seen this somewhere but can't get google to remind me where.)
- Someone edits a wiki page or adds a comment.
- The change is suspended until "authenticated".
- At this point the person enters an email address (of some determinably accountable, non-transient nature).
- The change or some indication is sent to the email address.
- Upon receipt of the response or via an http form in the email, the change is accepted.
- In addition to other filtering and governing, the site now also has an email address.