The multiple IP code can be rewritten more efficiently like this:
--
$banned_addrs = array(
'nnn.nnn.nnn.nnn',
'nnn.nnn.nnn.nnn',
);
if (in_array($_SERVER['REMOTE_ADDR'], $banned_addrs))
die('<p>You are banned.</p>');
--
I attempted to wrap that in a CODE or PHP block but vBulletin seems to be a bit broken.