Bosu Balance Ball
I have "u-hem" entered into the middle stages of my life. One thing you learn very quickly is that your balance and core strength starts to erode. I recently started working out with a trainer and virtually all of our exercises revolve around weight training off the balance ball. The combination of an unstable surface--the balance ball--and free weight exercises is great for balance and core strength. I highly recommend this piece of equipment for any home gym.