I have admin approval enabled, so I get to check users before they are approved, if one "looks spammy" I dig deeper. I like the fact that i can get notified when more than one users logs in from the same ip address as well. So far I have had a few spammers hit, I have used .htaccess on my server to stop those ip addresses when I find them. Because I got very tired of bots hitting some web forms on my site, now the entire ip ranges of some isp's have been blocked... it's not very democratic, but this is a very local and specialized site so I really don't worry too much about it.
