Personally, I use DokuWiki for various things. Recently, I stumbled upon the Google 2Factor authentication and looked for a DokuWiki plugin. There was a very basic one, that only supported one static key for all users. Based on this implementation, I decided to create my own implementation.
This version supports multiple users with different keys, user self service via the Update Profile link, force and hint on non-existing keys as well as a very basic admin interface.
Find the code in my hg repository at www.aboehler.at/hg/authg2fa