My Top 3:
Drivers who travel well below the speed limit in areas with no passing lanes, leading a train of 20-30+ cars for 30+ kilometers without pulling over and letting them pass by. In particular, the road between Keremeos and Princeton as well as between Castlegar and Nelson.
Oncoming truckers who think that just because their cab has passed you that it's ok for them to continue cutting their corner. D@rned near cr@pped myself when I saw those huge tires cheating halfway into my lane heading straight for the hood of my car.
Drivers who don't look right before turning right at intersections, driveways, alleys, etc. I must admit, this one includes me, but after several near misses as a pedestrian on the sidewalk, I'm trying to make a conscious effort to look before turning.
What are yours?