One of the more annoying things about working with computers these days is having to remember a bazillion username/password combinations. There have been several attempts in the last few years at creating a viable single sign-on system, but none of them have been successful.
I think it’s mostly just been a social problem. Either people don’t want to trust their identity to a single authority like Microsoft, or else it’s just a chicken-egg thing. For whatever reason, these services have just not managed to gain any traction.
Now OpenID seems to be gaining some momentum. In short, OpenID is “an open, decentralized, free framework for user-centric digital identity.” The idea is that instead of logging into all your web sites with a separate username and password, you instead just use your OpenID, which is just some URI that identifies you — for example, http://pdubroy.myopenid.com, or //dubroy.com/patrick. The site then makes a request to that URI, to confirm that you are that person. In the worst case, you still have to enter a username and password for every site that you log into, but the username and password are always the same. But if your OpenID provider keeps you logged in via a cookie, then you only have to enter your password once, no matter how many sites you log into.
OpenID began with LiveJournal, which immediately gave it a decently-sized user base. Then, a few weeks ago, Microsoft announced that they would be integrating OpenID support into Vista. Now AOL has announced that every AOL/AIM account now has an OpenID URI. So, it definitely looks like OpenID might be getting enough support to actually be useful.
It’s not all rosy though. Many people have pointed out that the OpenID process is very susceptible to phishing attacks; but that’s a problem we’re going to have to solve somehow anyways, and I think the proposed solutions are pretty decent.