Spam-blocking stats for REALNEO: Aug 30th, 2008 through Feb 10th, 2009. We've seen quite a leap in activity very recently.
We currently use Mollom [1] (one of Dries [2]' newer projects) to protect the following forms:
All of the orange Spam attempts blocked you see in the image are attempts on those forms -- most likely, user registrations. You can barely see the green, which are non-spam attempts.
Mollom will also add filtering to the following forms as well:
We could expand filtering to content/comment posting, but this might raise the barrier to participation on the site, (as some forms would require a CAPTCHA,) and very quickly put us beyond the limitations of the free version of Mollom's service.
We could switch to a free module that provides CAPTCHA alone, (as opposed to Mollom's more active filtering,) but unless we do want CAPTCHAs on all forms, Mollom seems to be doing fine right now. I think some of the spam we've seen lately are actually human-driven anyway, which a CAPTCHA would not do much to prevent.
Links:
[1] http://mollom.com/
[2] http://buytaert.net/