I'm on facebook and twitter and Linkedin, but I don't embrace it as much as others. I use facebook to chat with a friend, play games, and keep up with various people. Twitter is really following news and if there is something wacky going on in a sporting event, than jumping into a conversation is cool. I usually get pretty ignored though. As for LinkedIn, I really need to embrace it a lot more considering it is a helpful tool to find a job.
I have been considering closing my facebook account though. For one, I just don't like the changes, and the facebook I signed up for is nowhere near the facebook I like today. Perhaps it was inevitable, but it really has gotten too corporate and bland. It's lost personality. Also, if I see another page I subscribe to say Like or Share this comment or some stupid thing, I might unsubscribe.