A few years ago, Martin covered OpenID, an open authentication system. Since then, it has become increasingly popular and a wide range of sites, from AOL to LiveJournal provide OpenIDs, and OpenID login is also quite common. OpenID is particularly popular for blog comments, with Blogger now integrating support for it.
An OpenID is an URL. [...]
Log in to websites with your site’s URL as your OpenID
Avoid multiple login names with OpenID
I really like the idea of an open and decentralized standard which allows you to sign in to
multiple websites without entering your username and password over and over again on every site that requires you to login to
vote (digg.com), comment, or participate in other means. There are so many sites where you have to login to use basically the same features that you used on another site just before you visited the new one.
