A guy or girl who is only attractive on the internet, thanks in large part to photo editing software and high-pixelation."
A girl looks amazing in her facebook or myspace photos. When you see her in person, she's fugly.
Of course, can work for guys too.
Attractive when interactive, unattractive in reality.
"That guy's totally intractive. He looks hot in his profile, but I've seen him in person and he looks nothing like that."