In the beginning, computers accepted input only from switches and punchcards. They slowly evolved keyboards, and eventually other forms of input were born, such as the mouse, joysticks, touchpads, touch screens, et cetera. But only recently have developments been looking to bring eye control to everyone. For many years, experimental technologies have allowed people with disabilities to use their eyes to control a PC. Lately, the same company that created the original mp3 codec, the Fraunhofer Institute for Industrial Engineering, has been developing a technology that brings eye GUI control to everyone. Being aimed at people with disabilities or difficult lines of work that require hands-free PC interaction, it tracks eye movements and stare durations to determine mouse movements and button clicks. They want to expand the technology far beyond just button pressing, as well:

Hermann also said that he forsees the day when by just looking at your stereo or a light panel, you could turn it on or off. He adds: "You could even control a kitchen display showing recipes or other information when your hands are busy or covered in ingredients."
While this is probably a long way off for the end user, it's a fascinating technology. Most people today can't fathom using a computer without a mouse. Perhaps in a few decades, the same can be said for an eye movement sensor.