This is what I use:
$site = (!preg_match('#^http://#', $_POST['c_site'])) ?
raw_param(trim(strip_tags("http:\/\/" . $_POST['c_site']))) :
raw_param(trim(strip_tags($_POST['c_site'])));
don't worry about raw_param, that's a function of my own, but you get the
idea.
