Light pen: Where desktop space is limited, it is used instead of a mouse or for
drawing applications where a graphics tablet might be too big

Temperature sensor: Automatic washing machines, automatic cookers, central heating
controllers, computer-controlled greenhouses, scientific experiments
and environmental monitoring.

Pressure sensor: Burglar alarms, automatic washing machines, robotics, production line
control, scientific experiments and environmental monitoring

Graphics tablet: Inputting freehand drawings or retouch photographs.

Light sensor: Computer controlled greenhouses, burglar alarm systems, robotics,
production line control, scientific experiments and environmental
monitoring.

Optical Mark Reader: Inputting pencil marks on a form such as a school register, candidate exam answers, any application involving input of a choice of options.

Optical Character Reader: :Inputting text to a computer ready for processing by another software package such as word processors, spreadsheets, databases etc.

Video camera: Inputting moving pictures, often pre-recorded, into a computer
 
Web cam: Inputting moving pictures from a fixed position into a computer.

Bar code Reader: Inputting code numbers from products at a POS terminal, library books
and membership numbers.