$$('input[rel]').each(function(el){  
    var prompt = el.get('rel');
    var pass = el.get('type') == 'password';
    el.addEvents({
        focus: function(){
            if (el.get('value') == prompt){
                el.set({value:'','class':''});
                if (pass) el.set('type','password');
            }
        },
        blur: function(){
            var val = el.get('value')
            if (!val || val == prompt){
               el.set({value:prompt,'class':'prompt'});
               if (pass) el.set('type','text');
            }
        }
    }).fireEvent('blur');
});