Project Honey Pot Http:BL allows you to verify IP addresses of clients connecting to your blog against the Project Honey Pot database.
!!UPDATE!! This plugin is no longer supported/updated as I have joined my development efforts with Jan Stepien and his original http:BL plugin. Please use http:BL plugin instead: http://wordpress.org/extend/plugins/httpbl/.
Project Honey Pot Http:BL allows you to verify visitors' IP address against the Project Honey Pot database. Using the Http:BL API, this plugin flags, logs, and blocks visitors with a high threat score, helping you prevent harvesters, spammers, or other suspicious bots from abusing your blog.
This plugin requires you to sign up for a free account at Project Honey Pot (http://www.projecthoneypot.org/?rf=45626) so that you can use their Http:BL API to verify your visitors.
This plugin is based on Jan Stepien's http:BL version 1.4 (http://wordpress.org/extend/plugins/httpbl/).