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
Xws is a text mode multi-player crossword and chat server. It presents the same puzzle to everyone, allowing people the option to try and/or discuss solutions. Play may be friendly collaboration or fierce competition, depending on the players' dispositions. Xws supports hundreds of puzzles in the popular Across Lite file format. Copyright issues prevent the distribution from including any puzzles, but several archives and resources are listed in the README.
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.