Skipping workouts because American Idol is on? No way! With the EnterTrainer (PowerUp Fitness; $100), a monitor lowers the TV’s volume if you drop below your target heart rate. Quit a workout; your TV quits too. And with the Exer-station (Powergrid Fitness; $200), your body, not a joystick, runs the video games. Who said TV isn’t good for you?