Uses built-in camera of your iPhone, iPod and iPad.
Cardiograph is an application, which measures your heart rate. You can save your results for future reference, and even keep track of multiple people with individual profiles.
Tries to be accurate may not be sometimes but somehow it manages to give results. Tried on my iPod and couldn't get it to work at first. Then tried again doing it under some light and it worked.
Although I'm still not sure if it gives the correct results or not..