Here's something the airlines should have done a long time ago.  American Airlines has announced that if you have just one carry on that will fit under the seat (no rolling luggage) you will be allowed to board before most of the other passengers.  This should help speed up departures considerably. 

 

I worked for the airlines long enough to know that a lot of the late departures, passengers are always complaining about, are caused by the passengers, themselves, trying to stuff most of their worldly possessions into the overhead compartments and taking their time about it while getting on and off the aircraft.