3D Ring

[SWF(width = 500, height=500)]
var ring:MovieClip = createRing();
ring.x = stage.stageWidth / 2;
ring.y = stage.stageHeight / 2;
addChild(ring);

function createRing(sectionNum:int = 30):MovieClip{
	var container:MovieClip = new MovieClip();
	container.circles = [];
	container.theta = 0;
	container.thetaDest = 0;
	var step:Number = (Math.PI * 2) / sectionNum;
	for (var i:int = 0; i<sectionNum; i++){
		var c:MovieClip = new MovieClip();
		with (c.graphics){
			lineStyle(0,0x000000);
			beginFill(0xCCCCCC);
			drawCircle(0,0,20);
		}
		c.thetaOffset = step * i;
		container.addChild(c);
		container.circles.push(c);
	}
	container.addEventListener(Event.ENTER_FRAME, onRun);
	return container;
}
function onRun(evt:Event):void {
	var container:MovieClip = MovieClip(evt.currentTarget);
	var num:int = container.circles.length;
	for (var i:int = 0; i<num; i++){
		var c:MovieClip = container.circles[i];
		var angle:Number = container.theta + c.thetaOffset;
		c.x = 200 * Math.cos(angle);
		c.y = 100 * Math.sin(angle);
		c.scaleX = (100 + c.y) / 120 + 0.2;
		c.scaleY = c.scaleX;
	}
	container.circles.sortOn("y", Array.NUMERIC);
	for (i = 0; i<num; i++){
		container.addChild(container.circles[i]);
	}
	if (container.mouseX < -100){
		container.thetaDest -= 0.05;
	}
	if (container.mouseX > 100){
		container.thetaDest += 0.05;
	}
	container.theta += (container.thetaDest  - container.theta) / 12;
	
}

This snippet shows how to create a 3D ring navigation using sine and cosine. Have a look: