The coolest use I've seen for the iPhone's flash is the Azumio heart rate app¹. It uses the flash to illuminate your finger, which you place over the lens of th

The coolest use I've seen for the iPhone's flash is the Azumio heart rate app¹. It uses the flash to illuminate your finger, which you place over the lens of the camera. And then they do some fantastic image processing (presumably comparing shades of red) to detect your pulse. ¹ http://www.azumio.com/apps/heart-rate/index.html http://www.azumio.com/apps/heart-rate/index.html