[Aziz Zaynutdinoff]

Писал в своё время для отсчёта под Halloween

this.onEnterFrame = function() {
	var deadline:Date = new Date(ГОД, МЕСЯЦ, ЧИСЛО);
	var nowDate:Date = new Date();
	var FullDayInMonth:Array = new Array(31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);
	FullDayInMonth[1] = (nowDate.getFullYear()%4 == 0) ? 29 : 28;
	//
	var cy:Boolean = (deadline.getFullYear() == nowDate.getFullYear()) ? true : false;
	//
	var monthFor:Number = (cy) ? deadline.getMonth()-nowDate.getMonth() : deadline.getMonth()+(12*(deadline.getFullYear()-nowDate.getFullYear()))-nowDate.getMonth();
	monthFor = (deadline.getDate()-nowDate.getDate()<0) ? monthFor-1 : monthFor;
	cy = (deadline.getDate()-nowDate.getDate()<0) ? true : false;
	var dayFor:Number = (cy) ? FullDayInMonth[nowDate.getMonth()]-nowDate.getDate()+deadline.getDate() : deadline.getDate()-nowDate.getDate();
	if (monthFor>0) {
		countdown = dayFor;
		var _check = nowDate.getMonth();
		for (var i:Number = 0; i<monthFor; i++) {
			_check = (_check > 11) ? 0 : _check;
			countdown += FullDayInMonth[_check];
			_check++;
		}
	} else {
		countdown = dayFor;
	}
	var strCount:String = countdown.toString();
	strCount = (strCount.length > 1) ? strCount.substr(1, strCount.length + 1) : strCount;
	var __int:Number = parseInt(strCount);
	if (__int < 5 && __int > 1){
		days = "дня";
	} else if (__int == 1){
		days = "день";
	} else if (__int > 5){
		days = "дней";
	}
};

Пользуйся только не забудь число поменять.