I've started to use a stability ball (never heard it called a swiss ball before, I guess it's the same) recently and I love it. I really don't know any good exercises for it. The exercises I usually do is get on my knees and balance without my hands for as long as I can, it really gets a good burn in your abs and hip muscles. I also just roll around with it, putting my weight into it and transitioning around it.
Oh and by the way! Stability ball + Jack & Coke = Bruised Elbow... found that out the hard way last night :icon_chee