Imagine if Siri knew everything in Apple's vast media library and could not only help you find what you're looking for, but download it instantly. For instance, you could say "Get the season finale of 'House.'" And even if you didn't know what you were looking for, Siri would help you narrow your search. "Siri, what's the first book in the '50 Shades' series?"
How about something a little more complicated? Tell Siri "subscribe to The New Yorker" and it would sign you up for the title in Apple's Newsstand and present you with a total before you say "Buy." Last but not least, it would be cool if you could say something like "Get 'Somebody That I Used to Know' and make it my ringtone."