Facebook make(s) it possible to remove someone as your friend. However, the dynamics of deletion can be quite dramatic, so for social engineering reasons, the systems notify users only when someone has added them as a friend -- no alerts or messages are sent when someone removes you as a friend. Thus a user has no easy way to find out if one of their "friends" has actually removed them. You can keep track of your friend count and try to remember who is no longer on your list, or periodically check your friends profile pages to see if you are still there, but all these approaches are generally frustrating and unmanageable. In thinking about this, I had an idea: to make an application that could tell you automatically when someone has removed you as a friend on a social networking service.

So Pell invented a new application, "Unfriender," with developer Siqi Chen. In their description of the application on Facebook, Pell and Chen write, "Do you ever worry that people you have added as friends on Facebook have secretly removed you from their friends list? Unfriender solves this problem by letting you know when people have unfriended you, easily and automatically."

So, in other words, you no longer have to wait until after the holiday season to see who sent you a greeting card and who didn't. If nothing else, applications like Unfriender will make you think twice about becoming friends with someone in the first place, knowing they'll be notified more easily - - electronically - - when you've eventually dumped them.