One of the feature (feature I must say) in Facebook Chat is the ability to appear online to only certain friends. Without this and with all your friends from childhood to adulthood, with family members and with all the girls you liked your Facebook chat would be lot messy and useless too.
- Open your Facebook Chat
- You'll see your friends inside the friend list.
- Each friend list has a green/gray status bar with a white circle.
- Click it to go offline/online for that friend list.