What about adding a hidden field to the submission form where if it contains a value upon submission, it's obviously spam filled in by the bot (if these are bot

What about adding a hidden field to the submission form where if it contains a value upon submission, it's obviously spam filled in by the bot (if these are bots and not actual people doing the submitting). Ryan Grove uses this technique on his blog and said it eliminated a lot of spam: "Yes. Riposte uses a very simple but very effective form of comment spam prevention: the comment form contains extra fields that are hidden from normal browsers via CSS but look like comment fields to spambots. When the form is submitted, if any of these fields contain content, Riposte denies the request. This technique has been in use for over a year at wonko.com and has been effective at stopping virtually all automated comment spam attempts."