Another idea would be to have a prediction market about all sorts of short-term events (e.g., in the next day/week) in Justin's life.

"How often will Justin go to the bathroom today?"

"How many hours will Emmett go without sleep?"

I can see it working, up untill the point the digg users arrive: "When will Justin totally bang a chick?!?"

that would be what is called self-fulfiling profecy...and it wouldn't work

Another idea applicable if this sort of thing becomes more popular would be to allow viewers to click on people in the live video feed who are broadcasting their lives to switch to those people's live feed.