Well, do you run or use the machines at the gym (or have a machine at home)? If so, keep it and learn about the iTrain and Cardio Coach workouts which can be done on your iPod (they have some great workouts).
Also, if it's a video iPod, then Cathe's putting together a way of downloading her workouts and mixing and matching them on a video iPod. You can then connect that to your TV and have incredible mish moshes.