I am annoyed by drivers who don't signal their turns, or start signaling after they have started their turns. Cyclists quite often need to know the driver's intention prior to the action in order to position properly. A lot of drivers don't really think about what they're doing. I'm convinced that this is why they get into traffic jams. Traffic for cars would flow much more smoothly if drivers thought about the entire system, and how their individual actions would impact the entire system, but of course, they don't. They just don't think. And this act of signalling after the turn initiated is proof of this - the signalling is not to let you know what they're going to do, it's to be in compliance with some law that says they have to signal. Idiots!

My other pet peeve is "sloppy driving." This manifests itself in drivers taking "the racing line" on left turns, where they take part of the opposing lane in completing their turn. Very sloppy. And very dangerous if you happen to be in that part of the opposing lane, waiting to make a left turn.

Luis