Sir-Uli

This plugin provides a possibility to block comments based on words of a predefined list. The built-in lists of wordpress only allow to send comments to the moderation- or to the spam-queue but not to block them completely. This is remedied with this plugin, which allows to block comments based on a definable list.
Attention #1: Use wordlist with care, there is no logging of the blocked comments!
Attention #2: It will also match inside words, so “press” will match “WordPress” as well!

WU – Block comments

This plugin provides a possibility to block comments based on words of a predefined list.

Simon Prosser

How it works.
The plugin monitors failed login attempts, if the limit is reached the users IP is added to a local banlist. 
The user is now blocked and can no longer attempt to login.
Every 24 hours the plugin will upload the blocker IPs and download a fresh list of all IPs blocked accross the network in the last 7 days.
If an IP is blocked on 3 or more servers its added the the global ban list and will be blocked on all servers using the plugin.

WU – Block comments vs WP-DenyHosts