I have posted how to do a correct woodchop with the swiss ball now I'm going to give you a whole workout using nothing but a swiss ball. Most people have one at home and struggle with the variation of exercises to do, so I hope this helps.
1 Woodchop from right to left
2 Woodchop from left to right
3 Side plank (left) ,How to do it : Place your elbow on the ball and lie across the ball in a split stance. Lean into the ball, push up with your elbow and keep a straight line down the centre of your body. Brace your abs and hold. Do it on both sides.
4 Side plank (right) Same as above but switch the hand your are leaning on.
5 Crunchies ,How to do it: With your feet flat on the floor, place your lower back on the ball and keep your upper body and thighs parallel to the floor. Do crunches as usual; use your abs to lift only your shoulders and upper back off the fitness ball.
6 Trunk extentions , How to do it: Get down on your knees and drape your upper body over the top of the ball, with your arms lightly hugging the back of the ball or with your hands behind your head. Lift your chest off the fitness ball until your spine is straight or slightly extended. Return to starting position.
To add a little twist to it complete each exercise for 45 secs, rest for 15 secs then move to the next exercise. When completed all 6, give yourself 2 mins rest then start the proccess again. The aim is to complete this workout 3 times and should'nt take you longer than 30 mins .
Good luck and let me know how you get on