This is an intriguing approach, Dre. I wonder how to render this non-problematic for folks with screen-readers too. You could just say "leave this field blank" but that's sort of weird too. Is there a WAI-ARIA approach that would get screen readers to hide this field too? 

I'm looking into Mollom too -- looks like that could work in a few areas of our site.

Thanks all!

-----Original Message-----
From: Code for Libraries [mailto:[log in to unmask]] On Behalf Of Andreas Orphanides
Sent: Monday, October 24, 2011 10:13 AM
To: [log in to unmask]
Subject: Re: [CODE4LIB] web spam block less awful than Captcha?

Here's a method that's by no means foolproof but is practically zero cost (you may be using a version already). Disclaimer -- I have not actually tested this to any extent:
Include a text input field in your form that needs to be blank for the form to validate in the back end. Keep the field hidden with CSS (or z-indexed behind another element, size set to zero, etc). Users will never see it, so their forms will validate; I doubt that most spambots are sophisticated enough to check whether a form field is hidden or obfuscated before filling it in. Then silently reject submissions with that field filled.
I am not sure whether this would cause any problems with tab navigation, screen readers or other assistive technologies, but you may be able to do something to sidestep those issues.... On the other hand, captcha brings its own host of accessibility problems.
One other disadvantage is that this might be hard to implement in a CMS-based form plugin. But if you're coding forms the old-fashioned way, it's worth a shot.