NewSignupPage

NewSignupPage is an extension written by Jack Phoenix (one of the administrators of the ShoutWiki service this wiki is hosted on) that greatly enhances the standard "create account" page.

It adds a disclaimer notice checkbox about how new users must agree to the site policies and rules before they join (if they don't check it, they can't create their account), which also doubles a nice way to deter spambots (on top of other methods).

Even better, if Social tool extensions are installed, it has further functionality that enhances those extensions and provides even more features to a MediaWiki installation.