Dasher

Dasher is an information-efficient text-entry interface, driven by natural continuous pointing gestures.

Dasher is a competitive text-entry system wherever a full-size keyboard cannot be used - for example, when operating a computer one-handed, by joystick, touchscreen, trackball, or mouse;
when operating a computer with zero hands (i.e., by head-mouse or by eyetracker);
on a palmtop computer;
on a wearable computer.