Getting screwed by fraudulent transactions? Keep the bastards out of your site and stop them from placing their bogus orders in the first place.
We have a database of currently over 9,000 open HTTP proxies that scammers, crackers, carders, PW sharers, and other fucktards might be using to access, defraud, deface, and otherwise mess with your sites. Gain the advantage by locking out these proxies ahead of time before someone uses one of them to cost you money.
Code your signup scripts to check the surfer's REMOTE_ADDR against the IPs of these known proxies, then download and update the list whenever you want. You can even download the whole proxy list as a ready-to-use .htaccess file (not suggested for hightraffic sites, a 9000 line Limit directive is no good for server performance).
OpenProxies.com Only $20/month.