onImagesLoad

gistfile1.js

// MooTools
var onImagesLoad = function(callback){
	var images = 0,
		check;
	$$("img").each(function(item, key){
		images++;
		var img = new Image();
		img.onload = function(){
			images--;
		};
		img.src = item.get("src");
	});
	check = setInterval(function(){
		if(images === 0){
			callback();
			clearInterval(check);
			return;
		}
	}, 50);
};

// jQuery
var onImagesLoad = function(callback){
	var images = 0,
		check;
	$("img").each(function(key){
		var item = $(this),
			img = new Image();
		images++;
		img.onload = function(){
			images--;
		};
		img.src = item.attr("src");
	});
	check = setInterval(function(){
		if(images === 0){
			callback();
			clearInterval(check);
			return;
		}
	}, 50);
};

// usage
onImagesLoad(function(){
	// do something once all images are loaded
});