The Faculty of Psychology at the University of Bergen collaborated with the Bergen Clinics Foundation in Norway to produce what's known as the "Bergen Facebook Addiction Scale". Using this scale, you can find out just how addicted you are to Facebook.

Ask yourself these questions:

• Do you spend a lot of time thinking about Facebook or plan use of Facebook?
• Do you feel an urge to use Facebook more and more?
• Do you use Facebook in order to forget about personal problems?
• Do you have tried to cut down on the use of Facebook without success?
• Do you become restless or troubled if you are prohibited from using Facebook?
• Do you use Facebook so much that it has had a negative impact on your job/studies?

...and then score them on the following scale: (1) very rarely, (2) rarely, (3) sometimes, (4) often, and (5) very often.

The creators of the scale did a study which showed that the symptoms of Facebook addiction are very similar to those of drug, alcohol and chemical addiction.

How addicted are you?

(Source)