During the last meeting we reached consensus about the account creation policy. We decided that everyone should be allowed to create an account, but those accounts need to be approved. As MediaWiki doesn't have things like email verification built in, we need to use an extension for it.
[This extension] allows email verification upon account creation, but it doesn't fill the need for manual verification
Account Invite (Proposed Solution)
[This extension] allows to signup for a account after an invitation. This fits the bill perfectly: someone could request an account. This can be done in person (the recommended way), via email, irc or even by phone. This way it is not that difficult to create a account, but not too easy either.