Live Television on Apple TV.
I feel if Apple can find a way to get live television on Apple TV, this would be one of the biggest hits. If they can find a way to rent shows to able able to compete with the cable and satellite operators, you could find an Apple TV in many homes. They could also find a way to add games and integration with the iphone/ipod touch and be able to watch content from the web. The recent upgrade is a huge step forward and this is going to be a huge product in the future and can become very profitable for Apple.