Today I got my OpenID. OpenID is an open, decentralized, free framework for user-centric digital identity. Ok. Now how does that help? There are so many sites out there which accept OpenID to login. The list of sites that accept OpenID are listed here. These include the most popular livejournal and Technorati.
To get an OpenID you can go to MyOpenID and register. There are a few other websites that offer this service.
Once you get your OpenID you can login to any site that supports it. Technically, this is equivalent to a Single Sign On but for various sites. I still have not found a compelling site that uses this technology. But in the years to come, this technology might pick up some speed.