Well – I created, in my program, a banned IP list and query it upon creation of a new comment for the slots. I also make it email me the results of the comment so that I know what is being attempted. Here is a list of the sites of this spammer (so far as (s)he has tried to spam me with):
xxhttp://dmoz.awardspace.com
xxhttp://pieroo.org (contains a ton of gambling pages)
xxhttp://all-result.us
xxhttp://21publish.de
Different Whois for all of them, though.