I bounce back and forth on this. I don't really feel like Facebook enriches my personal connections; it just lets me remain to a lot of people I'm not really connected to anymore. It's like having a system for maintaining lower tier friends. LinkedIn feels the same way: I have a huge network of people that are all talking, but none of it really does anything to enrich my career. I don't listen to them, they don't listen to me. When I need career advice, help with job hunts, etc. I call someone I know and trust and they do the same. I don't think we can feasibly maintain large networks.