The best thing is, Tir, that most of them base THAT arguement on the story of Sodom and Gamorrah....and the more I think about that story, the less I believe it actually had anything to do with homosexuality. When the people of that place want the man to hand over his visitors, they want to beat them and steal from them. That would go against the laws of hospitality that many cultures had at the time.
Of course, when I start pointing out there may be another interpitation to ANYTHING in the bible, I get a slew of "lalalalala I can't hear you"!