Recently I heard of a nice, simple way to thwart spammers. Basically you push out a bogus input type=text field on a contact (or other) form, css it to display:none and check for its value on submit. If there is a value entered, then that means a non-human has been blanketing form fields, and the form post can be ignored as spam (and not handled).
I would like to turn this into a module, but I wouldn't know where to begin. It should be able to hook in to any module and federate form posts like the captcha module does, and it should not give the same text field label each time.. A random string would be fine, I think. Also, since spam bot authors love to target specific anti-spam workarounds like this one, maybe the field shouldn't generate display:none but rather jquery it in on load.