[bes]

<img src="http://javascript.ru/themes/defaultangy/images/home.gif">
<img src="http://javascript.ru/forum/images/ca_serenity/misc/logo.gif">

<script>
document.body.onclick = function (e) {
	var e = e || event;
	var target = e.target || e.srcElement;
	if (target.tagName == 'IMG') {
		alert(target.src.match(/[^\/]+(?=\.(gif|jpeg|jpg|png))/)[0]);
	}
}
</script>