[Admin]

Good addition, only one thing.
You should really replace this:

if (trim($bbuserinfo[signature])!= "")  $signaturechecked="checked";
    if ($bbuserinfo[emailnotification]!=0)  $emailchecked="checked";

With this:

    if (trim($bbuserinfo[signature]) != '') {
        $signaturechecked = 'checked';
    } else {
        $signaturechecked = '';
    }

    if ($bbuserinfo['emailnotification'])
        $emailchecked = 'checked';
    } else {
        $emailchecked = '';
    }

So people can't add stuff to the $emailchecked variable through the URL (this is why 2.2.5 was released).