Eye-tracking technology is a growing field used to detect eye movements and analyze human processing of visual information for interactive and diagnostic applications. Different domains in scientific research such as neuroscience, experimental psychology, computer science and human factors can benefit from eye-tracking methods and techniques to unobtrusively investigate the quantitative evidence underlying visual processes. In order to meet the experimental requirements concerning the variety of application fields, different gaze- and eye-tracking solutions using high-speed cameras are being developed (e.g., eye-tracking glasses, head-mounted or desk-mounted systems), which are also compatible with other analysis devices such as magnetic resonance imaging. This work presents an overview of the main application fields of eye-tracking methodology in psychological research. In particular, two innovative solutions will be shown: (1) the SMI RED-M eye-tracker, a high performance portable remote eye-tracker suitable for different settings, that requires maximum mobility and flexibility; (2) a wearable mobile gaze-tracking device--the SMI eye-tracking glasses--which is suitable for real-world and virtual environment research. For each kind of technology, the functions and different possibilities of application in experimental psychology will be described by focusing on some examples of experimental tasks (i.e., visual search, reading, natural tasks, scene viewing and other information processing) and theoretical approaches (e.g., embodied cognition).