Matthias-
I know it's a bold move but I want to propose a whitelist mode for article viewing. This is a feature that is most useful for Wikis with a closed user base. My implementation takes only few lines in Article.php and a new global config variable. Default action is - as usual - that everybody on this planet (or more precisely: in this net) can view everything. If the feature is turned on, only logged in users are able to view articles.
Instead of forcing people to log in, I would prefer a small box below the edit window for anons:
If you were logged in, your edit would be attributed, and you could change your [[Wikipedia:User preferences help|preferences]].
Username: Password: [log in and save] Password repeat: Email: [create an account and save]
But I have no objection to making the whitelist a sitewide option.
Regards,
Erik