<a id="on_off" data="Выключено" title='' href="#" onclick="this.title=this.getAttribute('data');this.setAttribute('data',this.innerHTML);this.innerHTML=this.title;this.title='';return false">Включено</a></br>
<a id="on_off" data="Cколько можно ?" title='' href="#" onclick="this.title=this.getAttribute('data');this.setAttribute('data',this.innerHTML);this.innerHTML=this.title;this.title='';return false">Включено</a>