I use a double pronged approach on some of my forms.
I have a field that must remain blank (or else it returns a message saying that we suspect you may be a machine). You have to be careful what you name those remain blank fields for a couple of reasons: 1) Google Toolbar autofill - it might stick a value in there unbeknownst to you and 2) It has to make sense to someone who might be seeing the field with a screen reader (maybe that's not an issue if you set the visibility off).
Secondarily I put a hidden field in my form that is populated when the onclick event fires on the submit button. I then check for that form value on the server side to make sure it's populated with the correct value. This should prevent bots from posting to my page. It basically requires the human interaction of clicking on the button to pass validation.
If you're interested in some code let me know.. I was going to blog about this, but have not gotten around to it.
I have been using reCAPTCHA (http://recaptcha.net/) on some of our forms with success. I am sure it will only be a period of time before this is useless as well. It has an audio CAPTCHA built in for accessibility, and is fairly easy to implement.
Seconded. I have had great results on our blogs with reCAPTCHA. The only spam comments that have come through are obviously human. Before that they were getting hit so much I have to have registration on, which meant no one went through the effort required to comment.
The forms we were having problems with did not ask for any urls. So, I wrote a script that checks each item in the object. If any of them contain "http://" then the script stops and returns to the form page.
The HighEdWeb 2020 Accessibility Summit is a one-day, online conference about digital accessibility in higher education happening June 25, 2020, from 10 a.m. to 5 p.m. CDT.Join in to learn best practices, share stories and connect with your higher ed peers on topics including social media accessibility, web development, user experience and more. Sessions are designed to boost knowledge at every level, from accessibility beginners to technical experts. Conference registration is $25, with…See More
October 19-20, 2020https://2020.highedweb.org/#HEWeb20 Join us ONLINE for HighEdWeb 2020, the conference created by and for higher education professionals across all departments and divisions. Together we explore and find solutions for the unique issues facing digital teams at colleges and universities. In 2020, the Conference will be held completely online, offering multiple tracks of streamed presentations, live…See More
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The 2020 Annual Conference of the Higher Education Web Professionals Association (HighEdWeb) will travel to Little Rock, Arkansas, this October 18-21 — and the call for proposals is now open! As a digital professional in higher education, we know you have great ideas and experiences to share. From developers, marketers and programmers to managers, designers, writers and all team members in-between, HighEdWeb provides valuable professional development for all who want to explore the unique…See More