Integrating web and specifically mobile technologies with the real world and physical products. Creating a seamless interface, some companies are just starting to explore this in the medical and entertainment areas. The next set of billion dollar companies should come from this area. It'll take awhile though since there are only a handful of people with the skill sets to launch and guide the companies.
A good point. People have been writing for a while about internet becoming more and more transparent as it becomes even more ubiquitous. I remember writing a paper about tv's with integrated imdb 12 years before the first app capable tv came out.
I think the other thing that I like about this sub-field, despite the fact that it's very doable by building on my current skills, is how it would integrate my love for hardware :)
