For those looking to strengthen...

[David]

Get yourself a rocker board...real good tool.
http://www.ballsnbands.com/theraband_rocker_board.html

[hernanu]

Very cool, David - I've been using a wooden rocker board at my gym, will have check this out.

[David]

I think it is probably the same thing/concept as the rocker board you are using Hernan.  I find it to be a great strenghtening tool though.

[Jagcanes]

Try using the Bosu ball.  It is a half ball that strengthens your core through balance.  I started out doing small squats and moved to one leg balance.  It really improved the muscles without stress on the hip joint.