WP-BlackCheck is an Anti-Spam Solution for WordPress blocking spam using local detection and a centralized Blacklist Service.
WP-BlackCheck combines various ideas to protect your blog from spam.
If you want to see this plugin in your language, feel free to contact me or use transifex.net to contribute.
Blocking spammers via htaccess or other server settings would do the job, but that would require to keep all the files in sync. So I decided to write a centralized solution that enables innocent users to remove their IP from the blacklist via removal request. As a blacklist gets queried way too often, I added some local detection of spammers to reduce load at my side. By now many additional features have been added, making this plugin a full grown anti-spam solution.