I've been asked to comment on whether I think bestiality is moral or immoral. This (like incest) came up in a conversation about homosexuality, which makes it a red herring, since the topics have absolutely nothing to do with each. Nonetheless, I thought I'd offer my views.
I believe that bestiality is wrong because animals are not consenting adults. You're raping the poor creature, which ranks up there among the worst kinds of animal abuse I can envision. That's wrong.
While I agree that such a thing should be punished, I do think the Bible takes the punishment a little too far. If I remember my Old Testament correctly, the perpetrator is to be executed; I don't necessarily think the crime warrants that.
The Old Testament also says the animal is to be killed as well. That's a bit harsh on the poor traumatized sheep, don't you think?