dircproxy is an IRC proxy server ("bouncer") designed for people who use IRC from lots of different workstations or clients, but wish to remain connected and see what they missed while they were away. You connect to IRC through dircproxy, and it keeps you connected to the server, even after you detach your client from it. While you're detached, it logs channel and private messages as well as important events, and when you reattach it'll download those logs to you using ordinary IRC protocol.
Spin Chat is a completely Java based Chat application, both server and client. It has been originally developed on Linux and runs excellent on it. It features vast customization possibilities, multi-channels, built-in spam control, graphical administration tools, I18N, channel logging, ignoring, emotes, etc.
Trebuchet Tk is a MUCK/MUSH/MOO GUI client written entirely in TCL/Tk. It supports both Unix/X11 and Windows, and includes powerful scripting, triggers, hilites, macros, quickbuttons, keybinds, etc. that you would expect from a good MU* client. It also supports MCP simple-edit, and GUI dialog packages for MOO and FBMUCK6. For Muck users, Trebuchet also supports intelligent colored editing of MUF and MPI programs.
savIRC is an IRC client for Linux, Unix, BSD, and Windows. It supports multiple server connections, SOCKS5 proxy, CTCP, DCC, passive DCC, ignore and notify lists, Unicode, mIRC colors, MDI dedicated windows, logs, customizable popups, pre-defined events, scripting in Tcl/Tk, captions for URL nicks, and channel names.
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.
The Interverse is the evolution and combination of the Web, chat, instant messaging (IM), and voice communication. It is not just a graphical user interface (GUI), but an immersive user interface (IUI). The Interverse is a virtual universe running on top of the Internet. It uses the Crystal Space 3D engine to render the user's view of the world.