If you ever go to a hospital, they have this thing they clamp onto your finger (very gently) and they can get the pulse from that. It's called a doximeter. It works by measuring the flow of blood through your blood vessels in your finger by shining a bright light into it and detect the difference in blood flow.
Guess, what, your phone can do the same thing, with this ap... It can use the camera and the "flash" LED. Just hold your finger over the camera, and wait. Really, it does work.
The pro version can keep a log of results, but the free version works fine.
Rating: Get it