- allow who is online to be totally disabled.
- allow member list to be totally disabled.
- disallow certain usergroup (such as unregistered users) to view member profile page.
Note : i've used add on to handle this, but i think this should be core because it is basic function for anonymity / saving server resource.
While disallowing unregistered users to view member profile page will discourage spammer, because some spammers just register, put link on their profile page, and never post / anything. So they rely on google (unregistered user) visiting their profile page and index their links.