On the topic of fake/spam users, is it possible and/or adviceable to protect the user profiles behind login? The forum itself can be world readable, but in order to see someone's profile, I would suggest to require a login.
This is not due to privacy, but because since the end of November 2005, this forum has gained about 150 members, of which more than 50% are fake users. I don't know how many who even activated the account, and whether inactive members show up in the lists. In the homepage link, they put in a porn, gambling, drugs or other URL. It can be a matter of policy which kinds of websites users are supposed to link to, but in this case the primary reason is to get a referral link, so Google and other search engines will promote that particular page based on how many other sites link there.
The user profile page thus will be considered a referral page. Some sites have been credited with a handful or even more "users". If the profile (and member list) is not visible for guests, search engine spiders will fail to find the page, and the link is worthless since the search engine doesn't know it is there. People who put spam links in their signature and post a single nonsense message are already taken care of, I've noticed.