IRChat is a plugin started in late July 2012. IRChat is developed by tommykins20. :) This is really old and is now an abandoned project but I'm going to edit this README for the fun of it. This plugin uses a Java IRC bot to connect to IRC servers and messages received from the IRC channel will be announced to the server and messages are sent to the IRC channel when a player has sent a chat message.
This Bukkit plugin uses PircBotX (an improved version of the PircBot API)