From the Web Development Blog, there's a quick tutorial posted about using the PHProxy package and ip2nation tool to save you some money on your bandwidth bills each month.

If your website becomes a little busy the websites bandwidth becomes very valuable. If your visitors using too much bandwidth and the conversions from your website are very low or just moderate, it’s possible that you get broke with also a good internet website project.

Their solution uses the PHProxy functionality and the IP address information (database dump) from ip2nation to create targeted user content. They include the setup for the proxy as well as some code that will need to be inserted to use the ip2nation data. Last but not least, there's also the code to insert into the page and make the magic happen.