We had trouble on the Nemo blog because some stinky casino spam overlord had found our nice little blog. Luckily the spam started of slow so I had a change to try different solutions to fight the problem. I went trough updating wordpress, to update Peter’s Custom Anti-Spam, to installing akismet, to try reCAPTCHA before I found the perfect solution WP hashcash. None of the other techniques got 100% of the spam. The wordpress plugin uses the clever hashcash technique (first proposed to fight email spam) implemented in javascript, to force a poster to pay a small amout of cpu time for each post. Supposedly though, the biggest effect just from requiring the client to have javascript installed in order to post 😉