360
It would be worth a look at your inteneded service area... do you just want your site to serve a region such as United States and Canada, or just europe, but you are getting lots of spam from locations irrelevant to your service area like Nigeria or Argentina?. Then you could go the LARGE htacces route and filter out (or filter in) IP address ranges of entire nations, or group of nations. blockacoutry.com used to provide the entire htaccess code with IP data by nation but I just checked and it seems like they are having a little bit of trouble staying online. I once blocked out all of Ukraine this way, as it was a beehive of spam.