No, but I wish I had. My brother asked me to be godmother to his child, and I reluctantly agreed. Both he and his ex-wife are anything but practicing Catholics, and we're separated by 500 miles. I don't have any control over what happens.
Part of the reason why I agreed in the first place is that I thought godparents picked up spiritual education and nurturing IF the parents died. And although some people say this is how it is. Others disagree and say you have to be involved in their spiritual nurturing WITH the parents.
I wish I had never agreed, even if it would have hurt my brother. But they don't take it seriously. I really don't know why they even bothered. My brother used to attend a seminarian preparatory high school and fell away from the Church soon after. The mother of the children is dear to me but was never nurtured beyond Baptism. In fact, when the mood strikes her to be spiritual, it's often in a non-Catholic atmosphere.
My last attempt was to offer to pay for Catechism classes for both of my nephews, and she refused saying it would confuse them because they attend a non-Catholic Christian school, and they aren't practicing Catholics anyway.
I feel helpless, but I can't overstep my bounds with the kids' mother (or father).
If I would have known that my responsibilities would take effect now, and had nothing to do with whether or not the parents were around, I would have most definitely refused and not thought twice about it. :(