we're currently creating such a system for our site. It works as a standalone apllication which can be integrated into any existing site. But it will use the user-db of threads for the usermanagement. It isn't finished, because it's a spare time project. I'll send you a PM with a link to the prototyp.
Donate to UBBDev today to help aid in Operational, Server and Script Maintenance, and Development costs.
Please also see our parent organization VNC Web Services if you're in the need of a new UBB.threads Install or Upgrade, Site/Server Migrations, or Security and Coding Services.