While exchanging a few comments on Stephen Johnston's blog as a result of his post about the Livebookings Diner Booking Interface (duh, DBI for short) with regards to user registration he came up with a brilliant suggestion that never occured to me before.
Portable authentication was all the rage a few years back, where users would be expected to register with one "master service", and other sites then integrate with the "central sign on service" to authenticate users. Like Microsoft Passport (aka Windows Live ID apparently). Users would only have to remember one set of credentials, web sites wouldn't have to build their own user registration, storage and authentication facilities. Great idea, never really took off for some reason. Not invented here?
Anyway. A site that is currently incredibly well positioned to deliver such a portable authentication scheme is Facebook. Now, not being a developer I haven't looked into the Facebook API in detail I am not sure this is currently possible, but it certainly should be. Instead of asking users to register with our own services, we could ask them to sign in using their Facebook user name and password, authenticate the user against the Facebook API and if ok get their profile data and let them into the service.
What hints against it is that to use the Facebook API I think one has to go through their servers, deploying your application through the Facebook site framework. Certainly would be interesting to look into though, and as a complement to register in our services use your already existing Facebook user to gain access / prepopulate contact detail forms.

