A little insignia that indicates you actually know a person as opposed to just being part of your “network.” Any time I need an intro at LinkedIn I always email the person who I’m connected to and check whether or not they actually are. Allow me to quote one friend’s response:
Good news: Sent an intro.
Bad news: I don’t know who the f- he is.
That is the point at which the utility of LinkedIn et al. starts to break