One who obsessively tweets, FB updates, blogs, posts video of himself all in the name of shameless self-promotion (generally without actually having a skill or talent to promote)
Mark can't stop publicizing the minutiae of his life- in the twelve status updates he posts daily, his twenty a day tweeting habit, his obsession with posting vids of himself on Youtube doing nothing.
"Mark had pizza for lunch today."
"Mark is on an escalator".
"Mark is in a parking lot." No one cares Mark. Stop being such a techno-narcissist.