Doorbell adds a Doorbell to your Facebook Profile. You can choose between several styles of walls, bells and ring sounds. Your friends can ring it when they visit your profile and you can go to the Stats page to see who rang it and when. Doorbell also lets you compare how often your bell has been run versus your friends. See who’s profiles are the most popular. You can even browse your friends Stats pages to see who has been ringing their bell. Give it a try. Put a Doorbell on your Facebook Profile and see who rings.