Being the resident Level III referee, I'll explain the goal area's uses...
Obviously, goal kicks are taken from within the goal area. Any free kick awarded to the defending side where the infraction occurs inside the goal area may be taken from anywhere inside the goal area, as done with goal kicks.
If the attacking team is awarded an indirect free kick for an infraction that occurs inside the goal area, then it it taken from the line of the goal area which runs parallel to the goal line, nearest to where the infraction took place.
As well, when a drop ball occurs, it may not take place inside the goal area, but on the line parallel to the goal line, at the nearest location to the infraction, as done with attacking indirect free kicks.
And Dark_Soccer, I'm not sure how they teach the Laws of the Game in Australia, but never, ever should an indirect free kick moved to the edge of the penalty area. And if you've seen a penalty given for obstruction, then that referee was applying the Laws of the Game incorrectly.
They've basically been said by everyone, but Ian has given me the "final word" on matters dealing with the Laws of the Game.