balance discs?
http://www.nefitco.com/balancedisc2pack.html These can give you a good and safe workout providing you have something to hold on to at first. And they move ALL muscle groups. Just learn to use them safely.
Here is the whole 'menu' of 'boards' and such this place has. It's pretty cheap and fair w/shipping etc.
http://www.nefitco.com/balanceboard.html
Thing is...don't do this without professional instruction.... safety if foremost in the use of these things, especially if YOU are wobbly! It becomes more important then! - j