Have you all thought about just not watching? It's not your place to decide what everybody else watches (which is what you'd be doing by trying to get certain channels blocked). This is the US after all, not Cuba or China. I don't hear a rallying cry against the movie channels, which show much worse than anything Nick could ever show.
The difference is that Nick is a kid oriented network, the movie channels are not. Don't you agree that a network that is geared to children should act responsibly in what thye choose to air?