2. Don't allow links in comments:
This would make it impossible for spammers to score any links on your site. However, turning off links in comments means that any person commenting on your blog would not be able to include links to stories they mention, their own blog postings or other important sources of information online. If links are the currency of the Web, then this idea might bankrupt your discussion.

3. Try a blacklisting service:
If you use Movable Type, the new version 3.1 includes the MT-Blacklist plug-in. That means comments that include links to known spam sites will be automatically blocked. Of course, no blacklist is perfect, and the universe of sites to promote via spam is seemingly endless. But this method will at least keep some repeat offenders off your comments.

4. Redirect all links from your blog comments:
If comment links all are redirected through a special URL, then the offensive URL will get no boost in search engine results. Google's free Blogger software includes such a redirect via the link: http://blogger.com/redirect/?r=[URL to be linked]

5. Include registration steps or a comment preview page:
Any extra steps for comments takes away automated spamming techniques. Some bloggers have tried a "captcha" where people need to retype letters and numbers in an image before writing their comments. Others force every commentator to preview their comments before posting them.

And Six Apart created the TypeKey registration system so that commentators would have a universal log-in for every blog they want to comment on. Plus, Six Apart is providing code so that other software developers can implement TypeKey into their applications, making it a more universal service. Movable Type also has "comment throttling," limiting the number of posts someone (or some robot) can make in a certain time period.

Six Apart co-founder Ben Trott told me that people running high-traffic blogs will start requiring registration for comments. "This can be of benefit," he said, "since it has the dual effect of reducing comment spam and improving the general quality of the conversation because it tends to form a community of visitors around a Weblog."

The downside of registration is that spammers could simply register first and then spam. Plus, registration sets up a barrier for people who want to join the discussion. Usually, there's an e-mail verification for first-time commentators. But most bloggers would rather put a small burden on commentators than bearing the huge burden of fighting comment spam themselves.

6. Spell out the law:
One Irish blogger, Antoin O Lachtnain, was so upset after spending hours removing comment spam that he decided to post a special disclaimer for anyone who wanted to comment on his blog:

"Relevant comments are very welcome, whether you agree or disagree with what I have to say. However, advertising of goods or services is not permitted on this forum without payment of a fee. The fee per advertisement is 500 Euros, which is payable immediately by bank draft. If you post an ad but do not pay the charge immediately you have corrupted data on this Web site without my permission. As such, you are guilty of criminal damage under the Criminal Damage Act, 1991 and subject to a prison sentence of up to 10 years and a fine of up to 12,700 Euros...Please note that posting on this forum will have no effect whatsoever on the PageRank of any links that you post.So the question is, will commenting on blogs survive the onslaught of spammers? Duncan Riley, editor of the Blog Herald in Australia, thinks the dynamic will likely shift in the blogosphere, with mid-tier bloggers abandoning comments altogether.