BZFlag is a 3D, multiplayer, tank battle zone, capture the flag game that pits players against each other in a networked environment. It runs on Windows 95/98/NT/2000, Linux, MacOS 10.x, Irix, Solaris, and others. An OpenGL accelerator is highly recommended, but it is playable with 3D in software.
Pipo-BBS allows you to install a BBS server and clients. You can chat via a nice interface with an unlimited number of people (as with IRC). This software is in a pre-release state; it is still very alpha, and can be difficult to even compile. It works under linux, MkLinux, SGI, HP-UX, and Solaris. The only interface for this BBS is telnet for the moment; an interface using GTK has been started. It has been translated into French, English, Spanish and German.
Ncohafmuta is a text-based chat server that is designed for access from a telnet client. Its purpose is to allow users to communicate in a configurable environment in realtime. It allows users to create accounts with their own settings and optional personal information. Rooms are the basis for communication, whether private or public. Other features include internal email, email forwarding, a configure script for multiple Unices, support for cygwin under Win32, macros, games, a ranking system with access to more commands, ANSI coloring, banning, async DNS, soft/hot-rebooting, detailed, organized logging, and an internal Web server port.
Gangplank is a Computer Mediated Communication (CMC) system (or "chat server") which supports real-time communication between users, currently using a text-based user interface. It runs as an Internet server which implements the standard telnet protocol, so no special client program is necessary for users. Server-side processing provides input editing/history and terminal- handling features over the telnet connection for standard ANSI terminals. This code has been in production use on a private server since early 1993. This single-process server is fast, efficient and stable.
ngIRCd is a portable IRC daemon written from scratch. It is easy to configure, supports server links (even with original ircds) and runs on hosts with changing IP addresses (such as dial-in networks). Currently supported platforms are AIX, A/UX, Darwin/Mac OS X, FreeBSD, HP-UX, IRIX, Linux, NetBSD, SunOS/Solaris, and Windows with Cygwin.
ircproxy is an Internet Relay Chat Proxy, which works as a layer between your IRC client and the IRC server. It features bouncer capability and has more features, flexibility, and configuration options than other tools. It also includes an option to use the system password list instead of requiring a separate password database.