I've found the differences in free speech between some European countries and the US compelling. For example when Kurt Waldheim was elected in Austria, and he was a former Nazi intelligence officer. However Austria jailed David Irving for basically saying the Holocaust didn't happen. Now, that's an incredibly stupid and callous thing to say, however at least here in the US he should have the right to say it.
Penn and Teller also had that episode about the Vatican pressuring Italian officials to jail that Comidenne who's name escapes me, for saying the Pope would be sodomized by a big gay man in hell for his actions against gays. It didn't happen, but they sure tried.
I understand in the case of Nazi sympathizers and Holocaust deniers, I do. However "free speech" protects even the speech we hate, and especially that speech. When you start saying "Well you can't say X" it sets a precedent for anything offensive or stupid to come under the gun. This doesn't include assault and things of that nature of course.