Eye Tracking is indeed a very versatile tool and can be used in many different fields for studying and understanding Human behaviour as well as enhancing computer interaction by using the eyes. It is also gradually being introduced into the PC and Gaming Industry, for detecting drowsiness/fatigue in the Automotive Industry and in various other fields of Medical, Quality Assurance and Monitoring use.
The biggest field of use for Eye Tracking is still undoubtedly in the Academic and Scientific Research field, for Cognitive-, Development-, Experimental and Media Psychology in Neuroscience and in Ophthalmology. In Human-Computer Interaction, Industrial Design and for studying Mental Health Disorders etc. Another field where Eye Tracking is widely spread and used today is in the User Experience (UX) and Usability Testing / Research field.
Lately, Eye Tracking has also increased in use within the field of Market Research especially for Shopper Behavior Research, Package Design and Advertising. Many leading Brand owners within this segment now has their own Eye Tracking labs in order to effectively evaluate products etc.