David MacKay:

Keyboards are inefficient for two reasons: they do not exploit the redundancy in normal language; and they waste the fine analogue capabilities of the user’s motor system (fingers and eyes, for example). I describe a system intended to rectify both these inefficiencies. Dasher is a text-entry system in which a language model plays an integral role, and it’s driven by continuous gestures.

 

More infro and apps to play with it at http://www.inference.org.uk/dasher/

In my opinion, physical keyboards will always win, as they have a 1 to 1 relationship between thinking a letter and accessing that letter (for alphabets with a reasonable number of characters anyway). But this is a stunningly amazing improvement over eye tracked onscreen keyboards, and a fun thing to play with. Check out the scanning box method in the phone version. For someone with severe physical disabilities I think this would be best in class?