[Vertax]

Естественно самому.
Как вариант вот:

SIN = function (ANGLE) {return Math.sin(ANGLE * Math.PI / 180);}
COS = function (ANGLE) {return Math.cos(ANGLE * Math.PI / 180);}

MovieClip.prototype.arrowTo = function (X1, Y1, X2, Y2)
{
	angle = Math.floor(180 * Math.atan2((X2 - X1), (Y2 - Y1)) / Math.PI);
	this.moveTo(X1, Y1);
	this.lineTo(X2, Y2);
	this.lineTo(SIN(angle + 150) * 10 + X2, COS(angle + 150) * 10 + Y2);
	this.moveTo(X2, Y2);
	this.lineTo(SIN(angle - 150) * 10 + X2, COS(angle - 150) * 10 + Y2);
}

this.lineStyle(1, 0xFF0000);
this.arrowTo(100, 100, 200, 200);
this.arrowTo(200, 200, 400, 200);
this.arrowTo(400, 200, 50, 100);