I am using it to block all traffic from specific countries. You are absolutely right people get around IP address restrictions by using proxies or many other clever tools/methods however I can tell you from analyzing my own traffic that after I blocked a few countries the number of attacks reported by my IDS as well as the amount of spam has significantly decreased. It does not mean that I don't get attacks or spam but the number has been reduced substantially and the load on the servers has decreased substantially. In any case, I felt like maybe the community could benefit from this feature. I think pfSense is an awesome firewall, I have recently started using it and I love to see it grow quickly.