Comment spam is the bane of any blogger's existence. I, personally, don't get nearly as much as others I know get but it's still very annoying. I complained about it to Skadz and he told me how to tweak the SpamLookup Keywords plugin. He did not, however, mention what to tweak it with. Unlike mt-blacklist, there's no file (that I've found) filled with keywords and URLs to block. But I did find this. It's an extension to the SpamLookup plugin, and it's got some pretty cool little additions to it like the ability to block by url, content, email address, etc. Check it out.