Sometimes, I admittedly get (overly) worked up about speeders. It's mostly because I have a very relaxed, "cruiser" attitude towards interstate travel (which is where I spend the vast majority of my time driving.)
I don't drive around in town much. Usually just to go out and get fast food or groceries. But on the interstate, I usually always do the speed limit. My trips are usually days long. I know where I'm going and how long it will take. I know where I'm stopping for the night. So I hit the interstate, set the cruise control at 65, then try to relax and listen to some books on CD or some music, or just clear my head a bit. But I've also learned over my many traveled miles, that people are downright assholes. They don't care about me, my family, our car, our safety, the environment, anything. Only that they get where they're going as quickly as their vehicle will allow them to within whatever limits.
I shouldn't be TOO harsh, because most of the time, people will just leave me alone over in the slow lane, plodding along. But I always have run-ins with the countless assholes who seem to have some personal vendetta against me, simply because I'm traveling more slowly then they are. I've had people honk, high beam, tailgate, wave, flip me off, shout, spray wiper fluid, and even toss garbage at me for forcing them to move over a lane and go around me.
I've even had to do "extreme" stuff (in my opinion) like reverse pass people. I had one guy ride my ass on a two lane road, at night, with his high beams on. He's in some generic Explorer sized SUV, I was driving the Toyota Matrix I had at the time. Of course his high beams are lighting up the inside of my car like it was day time. I had to adjust ALL of my mirrors to keep the beams from being reflected into my eyes (which were already screwed up from the when he approached me at 400mph.) I got so tired of him following me like this for a few *miles*, that I moved over into the next lane, slowed down, let him gun it like a big macho man, pass me, then move back over again. Of course with plenty of time to see him flip off his high beams seconds later. Of course, that experience was in South Carolina, so I can't say it was a surprise or anything.
I've never blocked traffic by doing the speed limit on a one lane road, for the record. If the road I'm on is one lane, I'll keep pace with the car in front of me. If I'm in the lead, I'll do minimum limit+5. I'll go up to +10, then to +15mph to keep the cars from bunching up behind me. But that's not good enough for some people either. I could probably count off at least a half dozen times in my years of driving that I've had to pull half off onto the shoulder and get people (usually one car) to go around me that insist on "chasing" me around some winding, one lane country road at night with their high beams on, blinding the ever loving crap out of me while I try to take some turn that I can no longer see due to floaters.
Take a half-assed US drivers "education" program that barely teaches kids how to handle a 4-cylinder, automatic, Chevy Malibu without popping every curb; sprinkle in distractions like cell phones, eating, drinking, makeup, newspapers, magazines, gameboys, laptops, getting dressed, shaving, oral sex, DVD players, navigational systems, and screaming kids in the back seat; completely disreguard any marked speed sign as absolute rubbish; add a dash of superiority complex; mix vigerously: voila, the average driver on the interstate.