1. Stopping too far out in an intersection
You see that big solid white stripe? Sure you do. It's there for a reason, which is why you should stop your car behind it. Not in front of it, not on it, not on it just a little bit. Behind it. Otherwise, you’re forcing pedestrians to walk that much closer to traffic as they go around you.
It also blocks the view of anyone in the right lane who wants to turn right on red. If they can't see around you, there's no way for them to know it's safe, and they're more likely to take a gamble. And if you're in the left lane, you're putting yourself too close to the oncoming cars that are turning left from the perpendicular street. And that's no bueno.
2. Creeping forward at a red light
There are two types of red-light creepers in this world. The first is the impatient fool at the front of the line who thinks edging forward is somehow going to make the light change faster. It isn't. The second is the guy behind you who stopped weirdly far away and is now slowly edging forward and distracting you in the rearview mirror with his intermittent scooting.