• все параметры и настройки локализованы в одном месте, а не хаотично разбросаны по классам проекта
• возможность вносить изменения в настройки и смотреть изменения без перекомпиляции проекта

<?xml version="1.0" encoding="UTF-8"?>
<settings>
	<app_settings>
		<property id="SCREEN_WIDTH" value="640" />
		<property id="SCREEN_HEIGHT" value="480" />
		<property id="FPS" value="50" />
		<property id="STAGE_SCALE_MODE" value="noScale" />
		<property id="PLAY_BUTTON_X" value="100" />
                ...................................................
	</app_settings>
</settings>

var s:Settings = Settings.getInstance();
			
stage.frameRate = s.FPS;
stage.scaleMode = s.STAGE_SCALE_MODE;
.......................................

package  
{
	import flash.events.ErrorEvent;
	import flash.events.Event;
	import flash.events.EventDispatcher;
	import flash.events.IEventDispatcher;
	import flash.net.URLLoader;
	import flash.net.URLRequest;
	import flash.utils.flash_proxy;
	import flash.utils.Proxy;

	public dynamic class Settings extends Proxy implements IEventDispatcher
	{
		
		public function Settings() 
		{
			if (m_instance)
				throw new Error("Use Settings.getInstance()");
			
			m_event_dispatcher = new EventDispatcher();
			var urlRequest:URLRequest = new URLRequest(m_url);
			m_url_loader = new URLLoader();
			m_url_loader.addEventListener("complete", onDataLoaded)
			m_url_loader.addEventListener("ioerror", onDataFailed)
			m_url_loader.load(urlRequest);
		}
		
		public static function getInstance():Settings 
		{
			if (m_instance == null) 
			{
				m_instance = new Settings();
			}
			
			return m_instance;
		}		
		
		private function onDataLoaded(e:Event):void 
		{
			m_data = XML(m_url_loader.data);
			
			dispatchEvent(new Event("SETTINGS_LOADED"));
		}		
		
		private function onDataFailed(e:ErrorEvent):void 
		{
			trace(e);
		}
		
		override flash_proxy function getProperty(name:*):*
		{
			var str:String = name; 

			return m_data.app_settings.property.(@id == str).@value;
		}		
		
		public function addEventListener(type:String, listener:Function, useCapture:Boolean = false, priority:int = 0, useWeakReference:Boolean = false):void 
		{
			m_event_dispatcher.addEventListener(type, listener, useCapture, priority, useWeakReference);
		}
		
		public function dispatchEvent(event:Event):Boolean 
		{
			return m_event_dispatcher.dispatchEvent(event);
		}
		
		public function hasEventListener(type:String):Boolean 
		{
			return m_event_dispatcher.hasEventListener(type);
		}	
		
		public function removeEventListener(type:String, listener:Function, useCapture:Boolean = false):void 
		{
			m_event_dispatcher.removeEventListener(type, listener, useCapture);
		}		
		
		public function willTrigger(type:String):Boolean 
		{
			return m_event_dispatcher.willTrigger(type);
		}
		
		private static var m_instance:Settings;
		
		private var m_url:String = "settings.xml";	
		private var m_url_loader:URLLoader;
		private var m_data:XML;
		private var m_event_dispatcher:EventDispatcher;
	}
}