Where to start...

1. Slow drivers in the fast (passing) lane... esp the ones that don't move after you flash/honk
2. The same drivers that are yapping on the cell phone so they're going 15 MPH under the limit
3. People that see the "NO TURN ON RED" sign but fail to read the 'WHEN PEDESTRIANS ARE PRESENT"
4. People that stop dead still until they can cut over to another lane blocking all traffic behind them
5. People that do not understand "zippering" to an offramp/onto traffic and stop until they get to the end of the ramp.

... and that's just from the top of my head.