If it's truly an emergency, use your emergency flashers (hazard lights, whatever you want to call them) to let other people know that it is, in fact, an emergency. Emergency is generally indicated by flashing lights, at least with automobiles (ambulance, police, fire truck, etc.....). It's a quick, safe, non-volatile way to allow people to know that there is a problem and you are in a hurry.
I hate drivers that think everyone else should get the hell out of their way just b/c they want to drive 10 or 20 over the speed limit. It's not your right to endanger MY life or anyone else's just b/c you think you need to drive fast, for whatever reason.
If you think driving fast makes a big difference, do some math. It in fact doesn't make a big difference at all, rarely more than a few minutes for any distance that most people normally drive.
Take a 30 mile trip for instance...say the speed limit is 60mph. That will get you there in 30 minutes...easy right? Ok, say you want to drive 10 over, at 70mpg...wow, it still takes 25.7 minutes. Just over 4 minutes saved...how often have you really gotten in trouble for being only 5 minutes late? And how often could you have prevented it if you had only planned ahead anyway? Last check-20mph over at 80mph....some idiots do this and over 30 miles, only save 7.5 minutes of time. Still under 10 minutes difference. You know what? If you drove 60mph and took an extra 7.5 minutes, you aren't even fashionably late yet...in fact, you're pretty much right on the money for almost everything except maybe work...but again-plan ahead. Don't hit the snooze button for the 10th time.
Rant over.