Net-Junkie: (Noun) a person who is addicted to the internet or spends a great deal of time surfing the web or 'Diving'. Net-junkies tend to not have lives, although, on rare occasions, one of them unwittingly downloads it from the internet.
Person 1: Oy? Where's Steve?
Person 2: Oh, Steve's on the Net again.
Person 1: He's such a Net-Junkie.