1. Motorists that don't signal
2. Motorists and cyclists with the "me first" to the red light mentality.
3. Pedestrians that assume because you are just a bike they can wander jaywalking across the road right in front of you and you won't hit them
4. Cyclists that pass right-turn signalling vehicles on the right
5. Cyclists that squeeze between a car and the curb at the red light effectively meaning the vehicle that got their first cannot proceed on the green light
6. Construction crews that leave the roadway in a bumpy state when they are done
Enh I better not keep going.