I had a whole essay I was prepared to write, but then my grandmother was hospitalized and things were looking really bad. Needless to say, my day's plans were derailed.
Instead, I would highly recommend these two documentaries I have recently watched on the issue. If you have ever had any doubts about the validity of gays and gay marriage, these two movies should change those views. If not beautifully made, they do at least portray real people and propose all the arguments that need to be heard world-wide.