NetHirc is a bad pun and a Net::IRC client. It is terminal-based, and it comes with many silly Nethack-inspired messages. NetHirc is very modular and extensible; if you know Perl, you can customize NetHirc, and reload your changes while it's running. If you don't know Perl, you can still customize all the messages and mold the client to look like you want it. If you've become frustrated with other IRC clients that have nasty scripting languages and take themselves too seriously, then NetHirc could be your ticket to enjoying IRC again.
NetPlug is an extensible multi-connections, multi-protocol, network client program, written in pure Tcl/Tk. Includes a complete Irc client plug in that you should love if you like IrcII 'classic' look & feel (plus customizable style/colors scheme, sound,... Now includes full DCC support (with GUI), ircII like aliases and improved scripting (Tcl!), keywords (your nick...) highlighting, and more
IRC Channel Relay Bot allows you to have an IRC channel span multiple IRC networks. It relays public and private messages, informs you about people joining and leaving the channel, and passes topics across networks (if you op it). It has minimal ability to help protect the channel.
XChat-XMMS allows XMMS to be controlled from within XChat. It can send out messages to channels or other IRC users, and supports searching playlists with Perl regular expresions, DCC transfers, understands MP3 and Ogg-Vorbis tags, caches playlists for quick searches, and allows remote playlist browsing via /msg. It also supports auto- messages and auto-topics.
Magick IRC services is a program that is designed to interface with an Internet Relay Chat (IRC) network, and offer its users, operators, and administrators services such as the ability to register nicknames so they cannot be taken by anyone else, the ability to register channels with pre-defined access lists and kick lists so that channels may not be taken over, the ability to leave offline messages for other users, and many network control mechanisms to stop things like flooding, abusive users, and many other things.
jIRCii is a cross platform Internet Relay Chat client. It is fully scriptable using a Perl-like language called sleep. The focus is to provide a console client experience with the advantages of a solid GUI. It includes DCC/CTCP support, the ability to connect to SSL servers, and over 65 built-in commands.