Leaving wheels turned is a huge pet hate of mine - I believe people do it to "protect" their car against someone clipping it. It seems they do not understand that the damage of someone smashing into your wheel is probably going to be far greater than clipping your wing or mirror.
I hate people that do not overtake slow vehicles/bikes, especially tractors - the amount of times I've had to overtake about 5 cars + tractor because those in front seem too incompetent to perform an overtake.
I hate people who seem to have to pull out of a junction and get as close to you as possible whilst doing so, when you're turning into the juction crossing their path.
I hate drivers who seem to think they are going fast enough in the outside lane, despite me coming up from behind much faster.
I hate people who slam their brakes on at the last minute if a traffic light goes amber. I also hate people who slow right down for a green traffic light, as if they are waiting for it to change.
I hate people who don't let others out - mostly when two lanes filter into one, but it is just annoying when you're trying to pull out of a junction into a queue.
Lastly, and this is probably more a local thing; people who seem to think our only dual carriageway is actually just one long filter lane - I often find myself having to undertake.