georf

This plugin uses JavaScript to verify that commentators are persons rather than bots.
If a user’s browser doesn’t support or allow JavaScript, so-called CAPTCHAs are used. The commentator has to enter a fruit name given as image before sending his or her comment.

Obstcha

Decent comment verification to avoid spam without user interaction.

A plugin to remove all pending comments from your DB in one click. A useful tool if you’ve been heavily spammed or have not managed your blog for a while and would just like a fresh start for your comments. Note that this will not modify any previous that are not marked as unapproved.

Bulk Comment Remove

A plugin to remove all pending comments from your DB in one click.

Obstcha vs Bulk Comment Remove