Spoiler ahead. Be warned..
In the movie Peggy Sue Got Married, there's a moment where she walks into a store and asks if panty hose has been invented yet. This imho is one of those kinds of products, and you and I are living now in the past, where it hasn't been invented yet.
As you're walking around in the world you have your point of view, and everyone else has their point of view. If you could see things through other people's eyes that would be pretty fantastic. So much so, that it'll spawn a new genre of art, a new media type, like YouTube videos or Vine 6-second videos, Instagram photos.
You can record images or video as you travel around and I can become you either in real-time or in a simulated real-time. I can watch you watch a place that I'm in. So I just capture what I see and you capture what you see, but I can be you and vice versa, at any time.
I like it because it goes places. A room with people doing this all of a sudden has another level of meta to it, where you watch people watch people watch people etc. And it's all done with technology that already exists, audio, video, the Internet.