I get easily pissed off when people have loud personal conversations in public places. Loud cell phone calls, too.
I also had the same pet peeve as Veronica, and it was my older relatives who addressed me as Mrs. Steve Crankin. But, they are all gone now. I don't mind Mrs., probably from all those years as a teacher. I am one of the few in my program at Lesley University that uses that title on my official correspondence; in fact I am one of the few in my program that has the same name as my DH. I use both my last names.
Oh yeah, and insufferable parents who carry on conversations about their precious darlings who are just going through the same normal developmental stages as every other kid on earth.