This is what i meant by proper gedarim. You are able to deny friend requests without the other person knowing (just press ignore). A general rule of thumb is to not allow members of the opposite gender (outside of your spouse) to be friends with you. If you stick to that you are fine. In addition my wife has access to my facebook account and can see it when ever she wants to.
@Health I dont really understand your going to facebook affecting you thing or people coming to you thing is – I have had facebook for 6 years and have never had that experience. There are privacy settings on facebook which can make you unsearchable if thats what u want. I think you might be confusing facebook with myspace which had some of those issues?
Finally saying facebook is like a disco is sophistry (like many other internet related mesholim). There is nothing inherently wrong with facebook.