I have taken to banning entire Chinese and Russian networks from access to the "ucp.php" page, which handles registration, login, etc. While it is unfortunate to have to do that, the vast majority of the spam seems to come from Chinese or Russian IPs. Given that this message board is in English I don't think that should affect many legit users, and besides, they'll still have access to VIEW any of the pages, just not post. I started with a long list of IP ranges I found online, and am adding to it as I find new spammers. Hopefully this will slow down the flow of spam...