Refer A Friend.

[Doc Great]

Thans, but maybe you (everyone who takes over this hack) should edit the sendmessage.php so that the new template gets cached

// pre-cache templates used by all actions
$globaltemplates = array(
	'mailform',
	'sendtofriend',
	'contactus',
	'contactus_option',
	'refertofriend',
	'newpost_errormessage',
);