Related conference-inspired rant:
People who stand IN the little sidewalk dip/ramp while they wait for the walk light in their direction to change, completely blocking your path to enter the crosswalk and cross the street in your direction, which currently has the go-ahead. Especially annoying when you're towing 80 pounds of conference-related baggage to the train station because, unlike your soft, coddled colleagues, you don't want to burden the taxpayers (yourself included) with cab fare for a 500m trip to the station.
(Really, rant aside, it was a chance to reflect on how fortunate I am to only need that dip when I am encumbered by massive luggage, and to ensure that I remain able-bodied into old age by using 'muscle over motor')