I like the idea of facebook but I really do not want to have everyone be able to see my friends and have friends see other friends...get it? I know you can do some of the blocking I want to do but it takes to much effort. My wife is on it so I can see enough of what is going on with a lot of people I know, whether I like it or not.
I do use LinkedIn which is kind of like a facebook for business. You can hide your friends there and it is a pretty nice networking tool especially for the business I am in. I like it to keep up with clients/friends from my accounting days, current clients of mine as well as a little bit of marketing.