There's a surprisingly wide array of devices for monitoring your heart rate on your iPhone, but Zensorium's Tinke is one of the more compact and attractive options we've come across. The small device plugs into an iOS dock connector, and provides heart rate, breathing rate, and oxygen content in the blood by bouncing infrared rays through your fingertip. The Tinke provides a reading within a few seconds, as well as a "Vita Index" that gives a relative measure of health on a 99 point scale. According to Wired, the device will be available in the middle of 2012, but eager hypochondriacs can sign up to reserve one on Zensorium's website right now.