Bukkit

This Plugin let you simply control the users indigence

Mutes chat for everyone without the permission to chat.

Automatically responds to frequently asked keywords

This plugin is a nice tag plugin that I guess it is important in hardcore games and full pvp servers.

BlockCmd

Kingdom Plugin

A simple autobroadcaster for your server!

A highly configurable ChatBot that acts as a friendly player on your server!

A better broadcast plugin. Super easy to configure, and make amazing!

Cross server chat

Hide login and logout messages, useful for compatibility with custom VariableTriggers login and logout messages.

OverPoweredPlugin

Full User Interface for your server !

Minecraft Social network server chatting

This plugins allows you to chat with a Bot in-game.

Full featured permission grouping with highly customizable chat formats

Prevent the use of MineChat clients through several features.

advanced spam protection

UCNJoinMessage is changing the way of welcome and leave messages!

NoServerMessages