Heres an odd concept. http://www.virtual-laser-keyboard.com/
I still prefer some form of tactile feed back or sound response when I type. But then again, I dont touch type and I still use the 4 finger method that requires eyeballs. One day I will force myself to learn that skill.
That laser keyboard has to be one of the worst ideas I've seen. As if standard keyboards didn't fsck up your fingers enough! A keyboard with no give in the buttons is just terrible.
Every time you hit a key, the stroke abruptly ends when the key reaches the bottom of the stroke. The key doesn't activate until it reaches the bottom of the stroke either, and the keysprings are designed in such a way that the resistance to the stroke is greatest mid-way down, instead of increasing throughout.
The result is a myriad little shocks up your fingers as you type, which is definitely not good for your hands. Laptop keyboards are even worse: the strokes are very short and sharp. Solid surfaces? Bloody awful.
The really old-fashioned keyboards, such as the old Model M, have entirely different keyspring/switch designs. The key activates about halfway down and the push resistance increases gradually, making the stroke bottom out naturally.
Far better for the hands, but they cost a hell of a lot more to produce. Modern keyboards cost about £10. Model M keyboards, assuming you can find them, cost about £80... and that's second-hand. I don't think they're still in production.