I have to admit, word verification and captcha codes keep the spam away, but they keep people away, too. I've been deterred from leaving comments many times because I often can't seem to get those darn letters and numbers right. I love it when they prod you with phrases like: "to prove you're a human," or "so we know you're not a robot." It makes me feel all warm-blooded inside when I try and FAIL, FAIL, FAIL.
My favorite verification comes in the form of a simple math problem, because while I seem to have problems with my vision when numbers and letters are purposefully distorted, I can add.
Are you a human or a robot?