Saw this thread (I'm aaware it's old)... I had to chime in. I've noticed some folks have a practice of creeping up on you and announcing their presence riding right off your return wheel. This is startling... and uncool. It's far better to announce your approach. Depending on your position, I might yield right away in anticipation.
Now for you impatient tailgaters ... your proximity is an iindication of your eagerness and ability to pass. So when you're tailgating and you DON'T PASS at a decent opportunity ... than you need to back off and cool your jets. I've seen guys past in shockingly small paces. If you can't pass in a 1.5 the width of a bike ... you should back off... you might find that 5-10 feet back is a better position to pass from.