I don't know if it's a skill, but it's the one essential I want in their toolkits and that is a passion for life long learning. I don't want them to ever get to the point where they feel like they know it all or have nowhere left to grow. I've seen too many people like that out there...with no drive to improve, no desire to excel, no passion for life. So that would be my goal to instill a passion for learning that is never quenched.
So far, so good :-)