Some consumer-research companies also employ goggle-mounted cameras to track eye movements so they can be sure what their subjects are looking at.

ECONOMIST: Facial monitoring

It tapped directly into long summer rides to Jones Beach with the dash-mounted eight-track blasting, to boom boxes in the Rockaways and Beach Haven, and turntables in back bedrooms of ethnic neighborhoods in the Bronx, Brooklyn, Queens and the burbs.

FORBES: The Night The Who Saved New York

He said small bio-metric monitors, mounted on chest belts, had been sent down to the miners to help keep track of their physical condition.

CNN: STORY HIGHLIGHTS