https://en.wikipedia.org/wiki/Google_Glass
A pure ingenious effort to turn humans into cyborg by adding the 4th dimension of computing to their lives in a non intrusive and seamless way. I can never understand why google couldn't make it popular given that wearable tech like watches and fitness band is catching up so quickly.
That being said, like someone else mentioned, Glass and AR-type products are very successful as productivity boosters in people who assemble products. We use Pupil Labs' glasses at our business to do gaze tracking. There's a lot of good use cases for this technology, but it's not cheap and it's pretty specific at this time.
Having some of the smartphone info in a HUD is a killer feature in itself, much better than a smartwatch.
Mostly in industrial use they are used to identify parts quickly with AR overlays.
Nobody could make it popular after that infamous shower photo. Products need certain coolness to gain traction and Scoble made it go the other way (I live in non-English speaking country and I use that shot to explain the word "nerd").
I'm not really that bothered by people holding phones in a way that might be surreptitiously recording me, because I expect they're actually using them for something else.