Facebook Faceless Friends
It's a Social Network
Personally, I don't understand why people use Facebook at all if they don't share some basic information about themselves with their friends and friends of friends.
I don't advocate that you open up information to anyone. In fact every user has to spend some time and understand that they are likely giving others too much access to information about themselves before they have screened them as good friends. Things like telephone numbers and addresses should not be set up to be viewed by just anyone. My choice is friends only.
At the same time, we can't be so paranoid that we block access to everyone and anything because Facebook is a social network and people need to use it that way. I have been fortunate enough to make some friends all over the world using this environment. As a writer, it has helped tremendously with opening up my mind to new and different ideas. The News Feeds that people post are a constant trigger for new ideas for storylines.
It isn't necessary to use an actual picture of yourself. In fact, I think it is more creative if you use something like the "postage stamp" that I created to denote that I am Canadian and a cheap date (lol). Use a picture of your favourite pet, or place or flower or a graphic you "borrow" from the Internet that tells us something about you.
If you don't want to communicate with the rest of the world, and learn new and interesting things, then don't bother with Facebook only to play Mafia Wars. Go to MySpace. It's so bad as a social network vehicle that no one will bother you. I have both. I have one friend on MySpace and several hundred in Facebook.