Block A Country is a neat little website that creates .htaccess rules to block entire countries from accessing your web sites.
This is used most often by web proxies whose owners don't want to be deluged by difficult to monetize traffic from places like Communist China and Iran.
With just a little bit of re-work, the output can be converted into firewall rules ttop this traffic before it ever reaches your web server.
BlockACountry was very useful to me last year, when my server was the subject of a DDOS attack from thousands of IP's across Turkey.
Unfortunately, the lists are not perfect. I received a report that I was accidentally blocking part of Greece with the filter.
With electronic terrorism becoming more popular every year, BlockACountry is a useful tool in the ongoing struggle against boorish behavior on the Internet.