HTMLHoverElement=Class.create()
HTMLHoverElement.prototype={

    initialize:function(el,out,over){
           this.element=$(el);
           this.outClass  = out  || '';
           this.overClass = over || '';
           this.element.observe('mouseover',this.mouseOver.bindAsEventListener(this))
           this.element.observe('mouseout' ,this.mouseOut.bindAsEventListener(this))
    },

    mouseOver:function(event){
       if(this.overClass)
            this.element.className=this.overClass;
    },

    mouseOut:function(event){
       if(this.outClass){
            this.element.className=this.outClass;
            }
    }
}

Element.addMethods({
  toggleClassOnHover: function(element,classOut,classOver) {
      new HTMLHoverElement(element,classOut,classOver)
    return element;
  }
});