Tetris Sand CA

stage.frameRate = 30;
scaleX = scaleY = 2.5;
var canvas:BitmapData = new BitmapData(200,200,false, 0x000000);
addChild(new Bitmap(canvas));
var w:int = canvas.width;
var size:int = canvas.width * canvas.height;
var read:Vector.<uint> = new Vector.<uint>(size);
var write:Vector.<uint> = new Vector.<uint>(size);

read = canvas.getVector(canvas.rect);
var loc:int = 199*w;
for(var i:int = 0; i <= 200; i++){
       read[loc+i]=0xFFFFFFFF;
}
write = read.concat();

var shapes:Array = [];
shapes[0] = [[1,1],[1,1]];
shapes[1] = [[1,1,1,1]];
shapes[2] = [[1],[1],[1],[1]];
shapes[3] = [[1,1,1],[0,1,0]];
shapes[4] = [[1,0],[1,1],[1,1],[0,1]];
shapes[5] = [[1,0,0],[1,1,1]];
shapes[6] = [[1,1,0], [0,1,1]];
shapes[7] = [[1,1], [1,0],[1,0]];
function drawShape(xp:int, yp:int, pattern:Array, col:uint):void{
	var i:int = 0;
	var loc:int = xp + yp * w;
	if (int(Math.random()*2) == 1){
		pattern.reverse();
	}
	if (int(Math.random()*2)){
		for (i= 0; i<pattern.length; i++){
			pattern[i].reverse();
		}
	}
	for (i = 0; i<pattern.length; i++){
		 for (var j:int = 0; j<pattern[i].length; j++){
			 if (pattern[i][j] == 1){
				write[loc + i * w + j] = col;
			 }
		}
	}
}

var counter:int = 0;
addEventListener(Event.ENTER_FRAME, onLoop);
function onLoop(evt:Event):void {
	 var i:int;
     canvas.lock();
	 if (counter % 20 == 1){
		for ( i= 0; i<20; i++){
			 drawShape(5+  i * 10, 10, shapes[int(Math.random() * shapes.length)], Math.random()*0xFFFFFF);
		}
	 }
	 counter++;
	 read = write.concat();
	 for (i = 0; i<size; i++){
		 var curr:uint = read[i];
		 if (curr != 0xFF000000 && curr != 0xFFFFFFFF){
			var below:uint = read[i + w];
			if (below == 0xFF000000 || below == curr){
			  var above:uint = read[i - w];
			  if (above == 0xFF000000){
				 write[i] = 0xFF000000;
			  }
			  write[i + w] = curr;
			}else{
				var index:uint;
				if (int(Math.random()*2) == 1){
					index = i + w - 1;
				}else{
					index = i + w + 1;
				}
				if (read[index] == 0xFF000000){
					write[index] = curr;
				}
			}
		 }
	 }
	 canvas.setVector(canvas.rect, write);
	 canvas.unlock();
}

Quickly thrown together sand cellular automata – with some tetris shapes.