Someone who spends the better part of their day in front of a computer screen. Usually spends this time idily surfing the 'Net, instant-messaging, forwarding messages, etc. (OK, it's the computer-geek version of a couch potato :P)
Jill: "Jack, what are you doing?"
Jack: (in front of a computer screen) "Ehm...surfing the 'Net...instant-messaging my friends...and other stuff..."
Jill: (sighs in exasperation) "Don't you have anything better to do with your time, cyber spud?!"