I have enabled the ability to use an OpenID identification to leave comments on this blog.
OpenID is a digital identity which allows you to log into many different websites without having to create a new login & password for each website. It's kind of like having a drivers license that can be used to identify yourself at various locations.
OpenID is not proprietary and is completely free. Additional information about what OpenID is and its benefits can be found here.
You can obtain an OpenID from several providers. I got mine from myOpenID. You might already have an OpenID and not even know it. Each of the following services automatically include an OpenID: AOL, LiveDoor, LiveJournal, Orange (France Telecom), SmugMug, Technorati, Vox, and WordPress.com.