Exercise ball is an excellent way to work out and gain balance.
This is what I have Gaiam Green Total Body Ball Kit - Medium : Target
I took it from the states to New Zealand.
It goes over everything... upper body, lower body, abs, fast cardio workouts.. and my balance has improved so much, and my muscles are toned (when I actually decide to work out.. been exhausted lately from work)
Highly recommend it. Anything from Gaiam is amazing.