var mailme = $$('.mailme'), at = / AT /, dot = / DOT /g;

mailme.each(function(el){
 var addr = el.get('text').replace(at, '@').replace(dot, '.');

 new Element('a', {
 href: 'mailto:'+ addr,
 html: addr
 }).inject(el, 'after');

 el.destroy();
});