It has become enough of an issue on my bbs'es that when new user req's come in, they do not get approved until I check their profile, ip address and email, any mismatch and the address or the entire cidr block if it is not a US or Canada ip end up in my htaccess file. (this wouldnt work well if there were more than 3-4 registrations a week.... then I would consider automating it.)
