Mollom

"We chose Mollom to solve our comment spam problem on Observer.com and haven't been disappointed. We received more than 5,000 comments on one popular story, and Mollom didn't even blink. Not only does it improve our user experience, it saves us many hours of moderation."
Brian Kroski, Vice President and General Manager, Online; Observer Media Group

"Mollom is a web site and protection moderation service which comprises some of the people who came up with the Drupal content management system, which is impressive. Right now they are concentrating on developing Spam filtering systems for companies, and they have already signed up a number of large players like MTV. It’s a hosted service with an open API. They don’t believe spam classification is binary (in the same way Akismet does)."
Mike Butcher, TechCrunch, Yes, even Belgium has startups

"I’ve been using Mollom (as a beta customer) for several months for one of the websites that I manage and the effectiveness of Mollom’s techniques are impressive."
Glenn Paulley, Sybase, Fighting spam with Mollom

"So, what makes Mollom different, from an end-user's point of view, than the other spam solutions I have tried (Akismet, Spam Karma, etc.)? Nothing, or rather, you have to do nothing, which is a whole lot less than what you do with the others. In fact, you don't have to deal with queues, moderation, constant attention and emails about all of the above. In other words you don't have to do anything. Oh, yeah, and the fact that it just plain works. I have yet to see a spam on my site."
Patrick Teglia, It's Best if You Don't See This

"I've been using Mollom for a few months and have been very happy with it. If you run a blog, even one that isn't in Drupal, I would encourage you to check it out. It's free for many uses, so you lose nothing by at least giving it a shot."
Justin Miller, Code Sorcery, Mollom anti-spam service is out of beta

"Before Mollom, I’ve been using spam.module and Akismet with varying degrees of success, and when Mollom first came out, I wondered why we needed another Akismet, but decided to try it out to support Dries. The answer to that question is that Mollom is in fact not just another Akismet. Spam blocking is just one of the things it does. That does not mean that Mollom is not good at blocking spam. My experience is that Mollom is more effective than Akismet and spam.module combined."
Mikkel Høgh, My six months with Mollom

"Mollom works differently. When you post a comment on CN, Mollom scans the comment and if Mollom thinks it might be spam, it sends you to the CAPTCHA page. So while a few real comments might get sent to the CAPTCHA page, the majority go through without ever knowing Mollom is active. Here's where Mollom gets bonus points. By sending the potential spams to the CAPTCHA page, I never see them and they aren't in a spam folder - they just don't make it. Hello one hour at the gym! So far, one spam comment made it to the live page - but it appears that comment was from a human."
Allen Stern, Center Networks, Mollom Just Gave Me Back An Hour Per Day