I just pulled the plug on Askimet. Why would I do this to a plugin that's been saving me about 1000 spam comments a day? Because once in a while it caught up a real comment. While I appreciate the effort these guys go through to thwart comment spam, one false positive is too many.
Instead I've installed the Did you pass math? plugin which asks a simple math question to test the human-ness (and basic intelligence) of the commenter. You'll see it above the comment field below unless you're logged in.
I first saw this plugin over at CostPerNews. Sam's been using it there for a few weeks now. Vlad raised the issue as well and in response to his entry, there's also a discussion going on at Bumpzee about it.
At first I was a bit put off by this plugin, not because I didn't want to use the brain cell to answer the question, but that I simply forgot to answer it. And when I did, I'd get a terse message, "Answer the question!" It seemed to me that it could have been a bit nicer about it, especially if I didn't see it in the first place. "What question???"
The other problem is that some browsers (Firefox) don't keep the form data when you hit the back button, also not a great user experience.
So I did a quick modification to the plugin to (a) make the error message a little nicer, and (b) give the user a chance to copy the text they just entered in.
Now instead of "Answer the question!", my error page looks like this:
Give it a try and let me know how it works. And if you want my modified plugin, let me know.
Here's my updated version of the did_you_pass_math.php file. It's got a .txt extension on it so you can view it. This replaces the file of the same name (minus the .txt) in the plugins directory. I didn't have to edit the language specific files in the subdirectories. This is only one of the files in this plugin. You should get the plugin at the source first, then replace this file. Enjoy.
I also made the field label red so that people wouldn't miss it.