There are plenty of apps that take advantage of your phone’s hardware to do obvious things. You can turn your phone into a GPS unit or even a compass by using the accelerometer and GPS receiver. You can use the camera for augmented reality apps. But every now and again a developer comes up with a way to use the hardware that just barely seems possible.
Instant heart rate is one of those apps. It’s a free Android app that measures your heart rate using the camera.
Basically you place your finger over the camera for about 10 seconds and it will start to monitor your blood flow. You have to hold your finger awfully close to the camera for it to work — but you also have to make sure not to press too tight or you’ll cut off blood flow.
Overall I’m not sure how much more practical this pulse rate monitor is than the old fashioned method of placing your fingers on a vein and counting. But that’s beside the point, because it’s incredibly awesome that it works at all.
The last app I saw that surprised me this much was probably Football Real Kick, an iPhone app that uses the speaker to blow enough air to kick a tiny spitball-sized soccer ball across a real table.
Instant heart rate is available as a free download from the Android Market.