Adidas' answer to the Nike+, the MiCoach Pacer adds heartbeat data to the slew of statistics it tracks during your runs. This lets Adidas create more advanced workout plans and training zones, with the on-board sensor alerting you if your heartbeat is above or below optimal range. As with Nike Plus, you can create online training regimens with recommended mileage for each day's run. A cheaper version, the MiCoach Zone, shows your heart rate and mileage, but lacks the fancy extras and the abilities to sync your data online. (MiCoach Pacer, $139)