Here's just a few:
I HATE those automated, ridiculously complicated telephone menus, "For x, press 1, for y, press 2"...ad infinitum, ad nauseam. Why can't I talk to a real person, right away? Even worse when you try to cheat by immediately pressing "0", which sometimes works, but then hear the message, "I'm sorry, that is not a valid entry." Then you have to hear the full recording over again. ARGH.
I hate people who habitually do not use their turn signals. PISSES ME OFF. They're there, use them, People. Please! A kitten dies somewhere every time you change lanes or make a turn without signaling. Think of the kittens, if not my nerves!
Not having a do-over button. Wouldn't it be great to be able to turn back time (sorry for stealing, Cher) and do things over on occasion?
That's it for now, I'm sure I have many more pet peeves, how about you?