Both sides on the whole passing lane issue are assholes, as it turns out.
The lane is a passing lane, not a fast lane, and if you are staying in that lane for more than a few seconds at a time you are doing it wrong, no matter how fast you are going. If you are not in the act of passing someone, move the fuck over. This goes for whether you are going 15 over or 10 under.
Now I admit I somtimes drive in the left lane during my commute, as it is smoother during part of it(middle lane has giant potholes and stuff). But if I see someone coming up in my mirror, I move over ASAP.
Now getting pissed because someone is taking a few seconds to notice you behind them and tailgating them is a double asshole penalty with a side of douchebaggery, thus negating any potential argument over whether the guy is driving too slow for the left lane. Also, intentionally holding up traffic in the left lane because you hate speeders and want to annoy them wins you the 'i'm a stupid vigilante who is going to cause more accidents than I prevent by forcing people to pass on the right instead of letting them go a few miles above the limit' award.
Aside from that, my peeves are people who don't signal or signal incorrectly, people who can't maintain a consistent speed for more than a few hundred feet (especially those 'gas>brake>gas>brake>gas even when no one is in front of me' assholes, come on, pick a pedal ffs), and last but not least, people who just don't pay attention. Cause you know, drinking your coffee or eating your hamburger, or making a phone call is more important than controlling the 2 ton piece of iron you are piloting down the road at 65 mph inches away from other cars with real live people in them.