We did something similar on Philosophy, where we designate one philosopher each week, and each person who asks a question relating to that philosopher will be eligible to win a prize. It's gotten a positive response so far, and we could easily adapt the model for this site - that is, designate a topic each week, and everyone who asks a question about it that week is entered into a drawing to win prizes.
We could start with questions about the new operating system, Ice Cream Sandwich, then move on app week, tablet week, etc.
What do you think? If you have suggestions for other weekly topics, please leave them here as well!
[Edit] It seems like there is a positive response to this idea, so we'll go ahead with it starting Monday 12/19. I'll make another meta post announcing the official rules then. In the meantime, keep thinking of other ideas for future weekly topics!