I have found that gesturing towards a driver coming from behind helps with situations where the driver may not know when it is safe to pass or not. In sections of road where right hooks are prevailant, or when there is a sharp bend in the road, I will gesture to cars to not pass (with palm turned toward them and waving them to slow down). Once the danger has passed, I wave them past me.
I also keep a close eye and ear to cars as I pass an intersection. It is possible to hear the signature of a car slowing to turn. If I hear this signature and see the car slowing and drawing level with me as I approach the intersection, I will accelerate and move my bike more toward the left to encourage the driver to slip in behind me and not cut me off.
I also ride toward the left side of the bike lane (if there is one) or toward the right tire track of the road if there is not (I encounter no WOL's in the area I ride). In a bike lane, I will position my wheels either on the white line, or only an inch or two to the right or left of it (I can ride a pretty straight line). This keeps me in the sight line of a driver passing me, but does not impede the driver's progress. I believe that most right hooks are due misjudgment of the cyclist's speed by the driver. Hanging all or part of the your bike and body into the driver's line of sight requires the driver to react, even if it is only to move six inches to the left to pass, and requires the driver to track your position closely and not misjudge your speed.
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Cat 2 Track, Cat 3 Road.
"If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --
the tiniest sprinter