I've always thought that for blog comments, the captcha should actually take the form of a few short SAT-style questions which would test reading comprehension.

I've always thought that for blog comments, the captcha should actually take the form of a few short SAT-style questions which would test reading comprehension. E.g. "Which one of the following is not one of the points the author is trying to make" "Which of the following best describes the authors' opinion of Java?" "What did the author cite as his source for his labor statistics?"