When pedestrians try to cross the street, there is often a large problem--that of a number of large heavy vehicles barrelling toward them in an offensive manner. It's as if the drivers were playing soccer, and felt a deep psychological need to knock you down before they took away the ball. Many drivers seem to be personally offended to have to wait the thirty seconds for a walker to cross. They will not slow down unless and until absolutely necessary in order to avoid manslaughter charges. Even at legitimate crosswalks, one is often hard pressed to find space. This is an especial problem if the crosswalk happens to be at a point where there is no stop sign or traffic light to regulate car flow. What is a poor lone walker to do?
Well, being polite helps. No, seriously. If a driver does voluntarily stop for you, whether they seem happy about it or not, look in their direction and wave to them; i.e., thank them for their courtesy in letting you cross. If possible, make eye contact as well. Then get across the street as quickly as possible.
Why should you do such a thing for aggressive drivers who are clearly out for blood (i.e. most of them)? Well, if you are polite (hence nice) to them, they might be less annoyed with you as a pedestrian. Hopefully this will make them a little less annoyed at pedestrians in general, and thus more likely to stop and let people cross the street in the future. They even may start to make eye contact and wave people across in a polite fashion themselves. You aren't going to be able to make drivers less late, or change their entire driving style, but you can make them conscious that you are a person, not an inconvenience.
Now, if the driver does not stop unless you are directly in front of them, that's a different story. Some people will stalk across the street, head held high, staring straight ahead in an offended fashion. Some people will stop dead and stare the driver down. Some people will yell at them. I tend to at least glare. While these methods are not as nice as the wave, they are clearly sometimes necessary. They certainly tell the driver that you are angry, and that running people down is not a god-given right. They will probably make the driver quite annoyed. But anger is not a bad thing to express, especially if, at some point, a given driver may actually commit vehicular manslaughter. Making them conscious of you in some way is, then, necessary, not just for you, but for the any number of pedestrians crossing the street in front of these drivers ever day.
And if you yourself are the driver, be conscious of the pedestrians, and of your own experience as a pedestrian. Really. Just because you are not one of them for the moment does not mean they are some alien entity. We are people; we walk.