Cardilio, a new app for iPhone and iPad developed by Harvard and MIT researchers, can calculate heart rate by merely gazing at your face. It uses your device's camera to measure tiny changes in blood flow in your face that occurs when your heart beats.
Simply line up your image with the displayed target, and the app reports your heart rate in seconds; when used in a well- lit environment, its accurate to within three beats per minute of devices used by doctors. You can track heart rate over time and get info about your fitness level and estimated life expectancy. The is available now on iTunes.