$(function(){
$("[src*='_off.']")
.mouseover(function(){$(this).attr("src",$(this).attr("src").replace(/^(.+)_off(\.[a-z]+)$/,"$1_on$2"));})
.mouseout(function(){$(this).attr("src",$(this).attr("src").replace(/^(.+)_on(\.[a-z]+)$/,"$1_off$2"));})
.each(function(init){$("<img>").attr("src",$(this).attr("src").replace(/^(.+)_off(\.[a-z]+)$/,"$1_on$2"));})
});