dogs on beaches and in elevators and restaurants,and people who let their dogs loose in public or let them jump up on everyone.
People who don't clean up after their dogs.
People talking at the movies, especially repeating everything you've just heard
I can't stand people who chew with their mouths open.
It drives me insane when i call up a company and I get "Dial 1 for X,2 for Y,9 for Z" and so on. Or the common assurance "Your call will be answered in the order it was received ," and then you have to listen to that boring music while they put you on hold.