Reduce the amount of information returned from standard service actions
For user objects specifically there's hook_services_account_object_alter(), e.g.

function MYMODULE_services_account_object_alter($account) {
  unset($account-&gt;mail);
}


For other entity/resource types there's hook_services_request_postprocess_alter(), e.g.

function MYMODULE_services_request_postprocess_alter($controller, $args, &amp;$result) {
  // Manipulate $result till your heart's content.
}