This is a general reply to the blase attitude towards the very life of others that some drivers here are espousing. So If you are a reasonably considerate driver, don't take it personally.
What is more important: that you get to where you're going fractionally faster or that you have respect for the safety of other people. In my country, over 3000 people die annually due to collisions with cars and most of those people are pedestrians or cyclists. Hundreds of thousands are injured. 2008 year was a good year and 'only' 2,943 were killed (this isn't a global figure, just in the UK). That's 2,943 families now missing loved ones. (http://www.guardian.co.uk/uk/2008/jun/27/transport1). That's a quarter of a million people since records began, in the UK alone (extrapolate for the world's population, that'd be closer to 25 million people killed on the worlds roads in the past 84 years).
Most drivers I encounter are polite and considerate and I'm polite and considerate right back to them - if I'm holding up a bunch of cars, I'll pull over to let them past if it's safe to do so as I want them driving up my arse about as much as they want to be held up by me.
However, most days I'll encounter some retard who thinks that driving like a lunatic is their god given right - these are the people who kill people like me and they should not be allowed on the roads.
If getting from A to B as fast as possible is, in fact, more important to you than somebody else's continued existence, let me put it to you in other terms: your journey is going to take a lot longer if you have to deal with the aftermath of killing a cyclist or pedestrian because you were driving too damn fast.