A registration with a common userbase?

Is anyone interested into establishing a user login class and infrastructure, a kind of passport system? The respective class would use an external or distributed database to validate the user against that database. It would also enable registration to that database, perhaps also adding additional data about that user to the central store. The class would also have an optional, local storage component with additional user data such as preferences, customizations and similar, which need or should not be shared to a central store. The class would allow a user to roam freely between sites that are using this class to authenticate users. Any ideas or voices on this? Kristian -- http://www.amazon.de/exec/obidos/wishlist/18E5SVQ5HJZXG