FiTrainer is an interesting product that combines headphones and a heart beat meter into one 
convenient unit. Featuring an ear clip that detects one’s heart rhythm, the system notifies the user of the current number via voice inside the headphones, which avoids having to manually check the reading on a display.
Features from the product page:
Complete 1 Unit Training System Heart Rate Sensor Equipped Chest Strap Heart Rate Monitor Voice Feedback Commands Training Rhythm & Music MP3 Player Compatible MP3 Integration Customized Exercise Modes PC/Mac Software Setup Minimum 15 hr. Battery Life
Product page: FiTrainer…