New update just submitted - added option to check the user's IP address and match country, state and city based on IP address. It also allows to check if user is behind a proxy, and if the IP is listed as a threat. The service requires an API key, but it's free for up to 10.000 lookups per month. Since the lookup is initiated only during the account creation process, this should be more than enough - it's highly unlikely that you'll have more than 10k signup attempts per month. And, if you actually do, this would mean you run a super-busy store and will easily be able to afford the paid plans...