The Galaxy S5 was launched earlier today at Mobile World Congress, and one of its headline features was the inclusion of a heart-rate monitor. You can already check your pulse with these iOS apps, both of which currently go for $1.99.
Both operate by placing your finger over the camera, and the app then takes a pulse from there. In my quick testing, both were very accurate, though you do need to have your finger placed flat against the lens. Heart Rate Monitor by Plus Sports also includes the ability to check your pulse by just looking at the front-facing camera.
I found that method to be a little less accurate, though still suitable for general purpose fitness needs. Obviously, these apps (and the Galaxy S5) aren’t replacements for medical equipment.
The other iOS app that can read your pulse has been around since 2011, and is named Instant Heart Rate.