When driving, what gets the most in your nerves?

I agree with Arainach. The other day, I was indicating to pull into the lane on my left, checked it and everything, all was good. So, I go to move over, and BAM! I nearly bang into a Mini, who is going into the lane from the other side...without indicating, and all the while yammering away on her mobile phone. I don't think she even realised how close she came to hitting me. ><

I hate tailgaters too. And people who drive right up your ass, flash you with their full beam headlights (while its still dark) just because you don't happen to be breaking the sound barrier at that particular point in time. (I hate this on multiple levels actually, the fact that they nearly blind you in the process and the fact that if you have to make an emergency stop theres sure to be an accident.)

Jam it back in, in the dark.