$(function(){
	$("img.swap").hover(function(){
		$(this).attr("src",$(this).attr("src").replace(/^(.+)(\.[a-z]+)$/, "$1_on$2"));
	},
	function(){
		$(this).attr("src",$(this).attr("src").replace(/^(.+)_on(\.[a-z]+)$/, "$1$2"));
	});
});