My biggest pet peeves are:

People who abuse animals/people;
Litterbugs;
Obnoxious children and their irresponsible parents;
People who don't take responsibility for their actions;
Children who interrupt or try to get in on an adult conversation (my friend's oldest son does that and it bugs the hell outta me!!);
People who ask questions that are none of their business just to be nosey;
Cat haters;
People who try to get into an elevator without letting the people out first;
People who THINK they are intimidating;
People who chew with their mouths open and talk with food in their mouth.

As far as the gay issue is concerned, I have always believed people should live their lives the way they choose without having to explain themselves. In today's world, there is always SOMEBODY who's gotta have a different view. I also believe that everyone is entitled to their own opinion. What I DON'T believe is that those opinions being shoved down other people's throats. To each his own.

If I think of anything else, I'll add to the list.