I know someone that's never signed up for Facebook. But they also track down every mention and photo of themselves on Facebook and ask people to remove them. Their extended network of family and friends helps remind others too, so they're completely invisible from Facebook.

It makes me think of GATTACA and Idiocracy, where this person lacks the instantly scannable bar code on their arm and how that makes them truly unknown to The System That Everyone Uses.

It occurs to me that if those are the first two movies people think of when comparing your social network to films, maybe something isn't quite right with your social network.