Spam ruins everything

So I have been forced to turned on "word verification" on our blog. What this means is that, if you want to post a comment, you'll have to do something to prove you're a human being. It usually consists of reading some funky-looking text, like this:


And typing in exactly what it says. This is something that's very difficult for a computer to do automatically, but relatively easy for a person to do.

I didn't want to use this feature, because it's annoying. But today we got comment-spammed (about 50 comments were posted in a 30 second period; all of them linked to shifty sales websites), so my hand has been forced.