A few days ago support for protecting deleted or not-yet-created pages from creation went live. Today I’ve also enabled Vasiliev’s TitleBlacklist extension, which allows admins to preemptively block potential titles via regular expressions.
Currently just the local blacklist is enabled, at MediaWiki:Titleblacklist on each wiki.
The regex behavior is a little different from the existing SpamBlacklist, so admins be sure to check the docs and test your entries. :) But it should come in rather handy for certain kinds of spam and silliness attacks.