social hub
(noun) A person who is the connection between networks of many different individuals and groups.
Mira has so many different groups of friends, she's such a social hub!
social network hub
An individual that is so important to a social network that they consistantly check landline voice mail, text message and send email to their social network at the same time!
Bobby: I went to see Nadine about some work, but she was very busy. She appeared to be talking on the phone and texting at the same time!
Mike: She is the social network hub of her apartment complex so you may be able to catch her tomorrow with work issues!
Mike: She is the social network hub of her apartment complex so you may be able to catch her tomorrow with work issues!