Cleantalk is a relatively cheap service which helps block spammers in WordPress and in PHPBB3, plus quite a few other software content management systems. I have been using it successfully on the Family Historian user group site for a few months and other than the human spammers it’s blocked the majority of the spam, far more than was being blocked by using a combination of questions, which new members got confused by and captures which people could not read.
I have recently paid to upgrade to a 3 site licence so I could also use it here on my Taubman site as well. As I mentioned it’s not expensive at around £6 per year per site and it’s blocked over 150 spammers in the week it’s been on this site and over 2,500 on FHUG since January. As I said it does sometimes miss a few, but on the plus side we have had very few false positives where users or their posts are rejected and you can provide feedback in the Cleantalk control panel for any it gets wrong.
If you have a commercial site, remember to include the fact you are using CleanTalk filtering in your Privacy Police.
For more information on CleanTalk you can visit their website here http://cleantalk.org/
Note: The CleanTalk links include a “partner ID” so if you sign up via my link I will get a little commission.