Comment spam - we all hate it. We operate numerous CMS and blogs and this is always a problem. We can stop most of the generic uncreative type idiots with .htaccess rules but others still go on. So we have started taking a more pro-active approach. We do a whois on their lousy domains and send emails to their admin contacts. If they have protected whois - we email the registrar with details of their activities (they probably don't give two f's...). In the emails we put a simple note of their feeble attempt to comment spam with a message that the next attempt will be considered an intrusion attempt as they are using automated scripts, and as such we will seek to bring charges against them in their local area. We also note that we will be contacting their hosts as well. We have never had to go that far as they never try a second time after these emails. Of course some admin contact emails never arrive or they comment spam with multiple domains at once with each showing different registrant information - for those we certainly flag their registrars for faking their registrant details. It only takes a minute a day. And after doing this for some three weeks the little buggers are starting to drop off and fast. Try it!
I maintain two wordpress blogs [1], [2] and I use the Banned Word list effectively to manage my comment spam. Q...
I added this to my blog right above the comment section "Note to spammers: rel="nofollow" will be added to all links in comments." 0 spammers since I put it in.
That worked for us on one site as well, but for the others, the calibre of the comments keeps us from doing that.
comment spammers are pretty easy to detect. In my photoblog, when I detect a comment spam I give a NSFW message to them and automatically add the class C they are on into my .htaccess file It took only 2-3 weeks and the spammers have kindly added around 300 Class C networks to my .htaccess file for me. Every time someone tries to comment spam me they block themselves from ever being able to di it again - Simple and effective. I like the idea about sending a note off to the whois contact - I might just go and code this myself as well!
Note: All spammers will face prosecution upon spamming our comments page(s). We are serious, we make money from you spammers