So shoot me, I nabbed the last one for 99 cents in a hoarder's panic: http://www.ebay.com/itm/5V-Heartbeat-Sensor-Senser-Detector-Module-By-Finger-For-Arduino/191129736978
Looks to be nothing more than an IR LED and phototransistor. Just like a line follower sensor. How well can this work? Has anyone tried one like this? Must be some signal conditioning required.
"When you make a thing, a thing that is new, it is so complicated making it that it is bound to be ugly. But those that make it after you, they don’t have to worry about making it. And they can make it pretty, and so everybody can like it when others make it after you."
- Pablo Picasso