Simple Math Problem (Score 1)

I personally just present a simple math problem that's randomly generated, e.g. what is 4 + 8? If the client doesn't get it correctly, then they can't post, create an account, etc. I've yet to encounter a spammer that uses a bot smart enough to answer that sort of question. Of course, this approach leaves out those with really low IQs or who haven't completed first grade, but I think I can live without their comments on my blog.