Using a heart rate monitor, a hacked MP3 player and a LilyPad Arduino, Dana Ramler and Holly Schmidt developed a wearable bio circuit:

With each beat of the heart, Bio Circuit connects the wearer with the inner workings of their body. In this sense the garment functions like other biofeedback devices that use sensors to provide a person with information about their physiological state. With Bio Circuit, we are proposing that these kinds of devices could extend a person's awareness to include the environment.

[via Fashioning Tech]