All the above plus:
The people who constantly get on their brakes for no reason. I can be on a road and there will be an idiot who is constantly hitting their brakes at every cross road, curve or any other reason. You don't know if they are going to turn, if they are going to stop for something or whatever. And the people who following in a long line of vehicles usually just under the speed limit, but they don't leave any room so you can't pass one vehicle at a time (leap frogging) you need to pass a whole stream of them at 20-30 mph over the limit. Really annoying!