You can't accept a new kind of computer into your heart if you don't have a good way to input text. Hardly anyone picked up a smartphone until BlackBerry solved the thumb keyboard, and still most people didn't pick up smartphones until Apple solved the touchscreen keyboard. Some devices, like Google Glass and Apple Watch, have an opportunity to be a new kind of computer, but without an obvious way to type on them, they seem awkward and unnecessary.
My own personal favorite wearable computing pioneer, Thad Starner, is famously proficient at one-handed typing with the Twiddler. It lets him take notes unobtrusively, or pull up references while talking to people. There have been many other one-handed keyboards attempted, but most of them rely on some sort of stable surface.
The upcoming Tap Strap, which has zero known affiliation with Thad Starner, is a keyboard made out of a flexible "smart-textile" which slides on over your fingers and recognizes your movements. You tap your fingers on any surface, and out come the words over Bluetooth to your device of choice. Each finger is a vowel, and combinations of fingers make up the other letters and symbols. There's no claim made on how fast you can type, but there is a training app to teach you — the learning curve is typically the biggest downside of any new text input method.
I hope Tap Strap is great, because I want to spend more time with heads-up displays and smartwatches, and less time thumb typing on my iPhone or doing two-handed QWERTY work on my laptop. Right now the device is in a "beta" of sorts, and will be made available to developers and other manufacturers to see what they can cook up with the new technology.
According to a Bloomberg report, Tap Strap should be in stores by the end of the year. The report also mentions that the final incarnation of the technology might be something that goes around your wrist, instead of this awkward finger-trapping version.