This topic from Long and Short Reviews hit home, because there is one thing that has always annoyed me and probably always will. And I really do wish more people had this ability.
The ability to follow directions.
Specifically, people who ask for directions in the street and then don't follow them.
I had a woman once ask me how to get to a building which was clearly visible across the street; I pointed it out and directed her to the crossing, and she walked six feet and asked someone else - who shrugged and told her he had no idea where it was. Well, I tried.
I also had quite a lot of people at a previous temp job who couldn't understand that they needed to turn right when coming out of a lift. Invariably they would turn left and then be surprised they were in the wrong place. I never did manage to figure that one out.
So what skill do you wish more people had?