I am in need of a user account bridge between XenForo and Craft (a PHP-based CMS that uses the Yii framework and has native support for plugins, as well as - with the Users package, which I own - profile fields, groups, permissions, and so on). Requirements: User accounts, groups, permissions, etc. are synchronised between the XenForo and Craft databases. Craft acts as the "controller" (registrations, validation emails, authentication, profile fields, permissions, etc. are handled through Craft). All in all, something a bit similar to the xF ↔ MediaWiki bridge. Shoot me a PM if you're interested in tackling this. Cheers.