Several months ago, I signed up for a 30 day challenge at About.com. I didn't do all of my challenges but one of favorites was a challenge to sit on a fitness ball for x amount of minutes.
I absolutely love my 10 Minute Solution: Fitness Ball Workout. I seldom do all the segments but I definitely make time for the upper body workout. There's a chest fly segment where your back is supported by the fitness ball then you sort of walk back up the ball in order to do the rear chest fly portion of the program. The ball has gotten away from me before. It's also gotten away from me while doing push-ups which is why it amuses me to see exercises like this one in various fitness magazines:
If I were to do the ball pike, I would be so injured. My coordination is good but not that good.
I did think about getting a fitness ball for my office but one of my friends nixed the idea. People already think you're interesting enough.