I got hacked 2 times in one week with my website. Since its a simple clan website and we never had interest in playing people from other countires (READ: LAG!) the thought came to my mind as I populated my IP Deny list to make my website US-accessible only. I know you will say \"yea, but what about script kiddies in the US?\" Well, i've really only had problems on foreign IP's.
You might have some luck if you use slow reverse DNS lookups and filter the top level domains. Like the .ca, .jp, etc. Though honestly that concept is very impractical.