I just saw a video of Monica Abbott throwing while on an exercise ball. Now that is dedication to your craft. I don't think it will do a lot to increase her speed or anything but it should help to keep her at the top of the heap as far as elite pitchers go.
The core is probably the most important part of an athletes body and that exercise will certainly get her softball specific core into top shape. I don't think I could even stay on the ball kneeling like that. You have to respect those top athletes, any sport for coming up with new and innovative drills to keep them in top shape.
As an athlete you probably understand how it gets a little boring doing the same thing over and over. Take a tip from Monica and try some little tweaks on your everyday drills.
Make it a competition with yourself or a friend, but mostly with yourself. Stand on one foot and try to swing the bat into a bag or at the cage. Stand on one foot to throw pitches. Stand flat footed and play catch using only your core and your arm. See how far apart you can get - no moving to catch bad throws either. If she makes a bad throw back to you she chases - same for you.
Just try to keep it exciting and new.