Sound Card ECG
The Sound Card ECG program provides a simple interface to view and measure ECG signals obtained through the sound card (using a line-in or microphone jack).
This is my heartbeat rate as I comfortably used the computer, then took a few minutes to watch a scary video (which elevated my heartrate for a few minutes in the middle).
Download Binary (SoundCardECG.exe)
Click-to-run binaries are provided with each release:
AD8232 ECG Module
DIY ECG with 1 Op-Amp
Those interested in building an ECG circuit from scratch may find my DIY ECG with a Single Op-Amp (an LM-741) project interesting.