The demos are really made to demonstrate some basic input/output usage. Combination apps are indeed where we think developers will find the most value. We plan to have an app gallery to show that soon. Thanks for the suggestion.
The part that they are doing next is: with the community of their users, they want to check the potential resonance of their marketing messages to those users, which they do with the Message Resonance service. Based on that, they can pick the most likely to be resonant message before sending it to the user.
see the movie "Her"
http://www.imdb.com/title/tt1798709/
how many people will fall in love with Watson?