Hearing aid technology. In the last decade, the biggest innovation has been to add Bluetooth to premium hearing aids. It's a total game-changer, but I'm very surprised that there hasn't been more innovation on this front. I'm profoundly deaf, and my hearing aid gives me so many cool features... but I can't help but wonder how much better someone with normal hearing would feel with those features as well. I'm practically a cyborg at the moment, with technology augmenting my crappy hearing. Why wouldn't a normal person want to be a cyborg too, and have tech-augmented super-hearing?!

Like many other things, I guess the demand just isn't there. And even though Bluetooth devices have made having things in your ear all the time way less stigmatized than they were when I was growing up, there's still a bit of embarrassment about having something like a hearing aid in your ear. It's a shame, really.