Simple question that blocks most spambots (and paid robots) by making them answer a common sense question
This plugin is just a very effective yet simple plugin which adds a question to the comment form that blocks most automated spam-bots by making them answer a common sense question. For optimal effectiveness, you should add multiple questions so that the spambots can't "memorize" the question and answer. The plugin will display questions at random to prevent the aformentioned memorization. Multiple answers can be added per question to account for variances in answers. (e.g. "five", "Five", "5")
Plugin homepage: http://www.compdigitec.com/apps/wpnobot
Please drop a comment if it works for you, if you found any bugs or if you have suggestions/ideas for this plugin - complaints welcome!