A startup in Austin, Texas, USA is in the prototype phase of development of a "keyboardless keyboard" accessory that allows a person to type on any surface or in the air. It is different from a project keyboard because it has no visual component. It uses a pair of cuff-like sensor units that fit around a person's hands and over their knuckles. The sensor units track your finger movements and then detect which keys you are striking if there was a real keyboard present. The device has some adaptive technology built in so that it can learn to adjust to a person's habits. They are designed to be small and mobile so they would work well with tablet or phablet devices.
