Clockwise from top left: Perfect for challenging both the core and the sense of balance, the BOSU ($100) takes any exercise up a notch. The Jungle Gym XT ($100) brings suspension workouts into the home — the system works with a door or a pull-up bar. Bring a little mind-body exercise into your fitness freak's home gym with a Pilates Spring Board ($445); it's a wall unit version of the classic Cadillac. If you feel like giving big, it's hard to go wrong with an elliptical by Precor ($3,400) — a joint-friendly cardio machine. A set of adustable dumbbells ($143) means more options that take up less space; perfect for strength training in a small space.