Typekey
The spec of TypeKey is available. And the mandatory perl module is also available :).
I really like web-based “centralized” authentication systems. It’s a nice stepping stone to more useful SIM-card or Smart-card based ones. It will keep me happy for a couple of months until I get decent support for smart cards in my OS of choice.
Update: and something new, at least for me, MyUID. Same thing, it seems, diferent implementation. From a quick glance to the PHP implementation (they don’t have a perl module), it seems to be a little bit more intrusive than TypeKey. You can pull a user profile from the MyUID server. Will see.