I get especially irritated at people who block sidewalks. I don't mind as much when you can tell that the person was getting into the driveway as much as they can, but run out of room, but when there is plenty of space in the drive and their car is blocking the whole sidewalk, I get pissed off. It wouldn't be that big of a deal, but I'm usually running, and when you're running, making unnecessary right angles is...frustrating.