people not saying thank you when you let them through, either doors or on the roads (chronic problem on the continent, you can always spot the English and Americans - they actually have some manners for the most part)
people standing directly in front of the door as youre trying to get off the train/bus/tram. Even worse are those who try and get on whilst youre getting off. (actually saw a guy miss his stop because people getting on wouldnt let him off. At the next stop, understandably pissed off, when the same thing happened he growled, yelled and shouted so loud that people thought he was insane and quickly got out of his way. As we pulled away i saw his face - sheer self-satisfaction and amusement. He became a mini-hero of mine)
people asking questions / for feedback then completely ignoring your answer / input even though it took you hours, days and even months in some cases to get everything together for them.
Scooter riders. I actually saw an accident with a scooter the other day, felt nothing. Usually say a quick prayer at vehicle crashes, but all I could think of was "well he probably cut the guy up and got what he deserved". Didnt feel bad about thinking that either.... No issue with proper motor bike riders because they dont harass people, nip through traffic scratching paint work. They wait their turn to pass and if you give them room, usually say thanks which, as point 1 of this rant might indicate, is highly appreciated....