I've been playing with some new api's latelty namely flickr and OpenAuth. I really like the idea
of using a single sign-on and not having to worry about building yet another authentication system
on a project. I was specifically playing around with HybridAuth and open authentication with Google, Yahoo, and AOL
and now I'm looking into leveraging Facebook's login as well. I implemented this on my Invoice website
InvoiceMe.
So far the tie in has been really nice, all you have to do is present a link for the user, they
put in their credentials into the system they are logging into and in return you get some profile data
which you can use to reauthenticate the user later. But the really nice thing is you never have to
worry about the user's passwords or them being forgotten.