Fully integrated augmented reality. Once we get mind-machine interfaces working, we could have an application that looks at every object around you, checks which one you're focusing on and somehow the entire Wikipedia article on it is already in your mind.
Then there was the internet of People (social networks).
And the internet of Places (maps, LBS, still happening).
Soon we will see the internet of _Objects_ and something like Google Goggles will be the key driver.
Documents -> People -> Places -> Objects. What's next?