public function UsernameAvailable($Name = '') {
      $this->_DeliveryType = DELIVERY_TYPE_BOOL;
      $Available = TRUE;
      if (C('Garden.Registration.NameUnique', TRUE) && $Name != '') {
         $UserModel = Gdn::UserModel();
         if ($UserModel->GetByUsername($Name))
            $Available = FALSE;
      }
      if (!$Available)
         $this->Form->AddError(sprintf(T('%s unavailable'), T('Name')));
         
      $this->Render();
   }