Wikimedia Bugzilla is closed!

My only major issue against using MediaWiki is it's lack of an access control
system. I don't like to say "this wiki has it so you should too", so I'm not
going to, and nor is it in every wiki out there, but I find it extremely useful.
For each page, one can assign an access control list, that looks like this:

Read    Write
-------------
*       $
        !12.34.56.78
        !SomeUser
        34.21.12.123
        Sysops

An asterisk denotes all, a dollar denotes logged in users. A hashmark at the
start of a line signifies a comment, and an exclamation mark at the start of a
line signifies inversion, so that  it explicitly forbids anyone matching that
entry. IP addressed would also be usable as entries, as would usernames, and
probably special usergroups (such as Sysops).