For me it is standing blocking doorways as they chat away. It is the total lack of awareness of other people that really annoys me.
That, and walking pass and loudly shrieking to their friend but aiming at my ear rather than theirs (does everyone have deaf friends????).
Those bloody scooters - especially in shops. People who spend ages answering their phones (when they have it in their hand, so you have to listen to their most uninteresting ring tone).
People who either stop right in front of you - especially on an escalator, or also on an escalator, suddenly dodge in front of you from the left hand side, as you are about to get off.
Oh and the right pillock who sits on the aisle seat and won't stand up to let me past, so i have to heave myself past him (pervert). My rule is , if someone is polite enough to say "excuse me please" as I do, then you move out the way for them. If they don't even grunt then just move your legs!!!
That's quite a list, I know.
Oh and people who ask when the next bus is. I look up and say, It says 5 minutes. If it is not there in exactly 5 minutes they get shirty about it.