I can't understand why rugby hasn't become popular in USA. It's our national sport over here and every American I have introduced to the game thinks it's great. I'm an American football fan too, but rugby is far more interesting to watch. The game is continuous, it doesn't start and stop as much as gridiron. American football is arguable more strategic but rugby is intense and makes for a better pub sport, in my opinion.
Edit - I'd like to add that although the vast majority of Kiwis think that Americans are total pussies for wearing pads and helmets, the hits in American football have the potential to be much harder so I can respect that. What I can't respect or understand is why they wear tights. It looks just plain gay.