Well, let's not all answer at once NIWA admins.
This thread might be helpful:
http://www.niwanetwork.org/forums/index.php?topic=1061.0I noticed that for Icaruspedia, you have the ConfirmEdit active for account creation. This is good, but humans and bots seem to have found a way around this. Either due to humans actively doing the spamming or programming a bot that can figure out the capture. Dragon Quest Wiki has the same problems.
From my point of view here are the options.
1) Let them spam and just delete it and block their accounts. This requires more input by admins, but allows you to keep registration open and useful for real users.
2) Change your autoconfirm age to be longer and only allow autoconfirmed users to create pages (and possibly edit). Spammers rarely want to sign up and come back later.
3) Turn off account creation. Create a page with an email address that users can email to have an account created for them. This is drastic, but I've seen it done on other wikis before when they just don't have time to deal with the spam.
http://www.mediawiki.org/wiki/Manual:Configuration_settingsThis page details how to adjust many of the wiki settings. Hopefully you have server access, otherwise you won't be able to do anything.