I was riding South along Aganier and came to the intersection with Summit. There is a kind of dog-leg intersection there; Aganier doesn't just go straight across Summit, but breaks and continues a little to the side. A van was going North on Aganier, approached the intersection from the other side of Summit, and stopped at the stop sign. I figured I had the right of way, and, in continuing on Aganier, I had to ride directly in front of the van. I remember thinking that I had crossed in front a little closer than I usually like to. As I crossed in front of the van, it began to move ahead, pushing me over before coming to a stop. I at first thought that the driver had become irritated with me because perhaps he thought I had unfairly taken the right of way, and I said something like "What are you doing?!". The driver got out and said, "I didn't see you". I said, "I was right in front of you!". And I had been using my flag, too. But the driver repeated, "I didn't see you. Are you all right?" As far as I could tell, I was OK, so I said "Yes", and, somewhat shaken, rode away. But as I rode away, I did feel some pain in one of my legs, which had apparently been twisted a little when I fell. I hoped it would just ride itself off, but it didn't, and some pain persisted for maybe as much as a week. I don't think any serious injury was done, but it seems as though I never fall but that some injury occurs, which at first seems rather trivial, but turns out to be worse and more long-lasting in its effects, than I would originally have thought.
So - it could have been much worse. I've had the same type of situation happen several times: a car comes to a stop, and I proceed. Then, as I'm moving in front of the car, the car starts to come forward, apparently unaware of my presence. I think part of it is - the drivers just aren't expecting to see a bike; they have their perception programmed for other cars. I guess this will change as more people ride bikes.