The SeaMonkey project is a community effort to develop an all-in-one Internet application suite. It contains an Internet browser, email and newsgroup client with an included Web feed reader, HTML editor, IRC chat, and Web development tools, and is sure to appeal to advanced users, Web developers, and corporate users. It uses much of the Mozilla source code powering such successful siblings as Firefox, Thunderbird, Camino, Sunbird, and Miro.
NetIRC2 is an easy-to-use .NET IRC client library. It supports all major features relevant to making a chat client or bot. It has full support for synchronization contexts. You can use it from a Windows Forms or WPF GUI thread and chat events will be automatically dispatched, allowing you to completely ignore multithreading. It uses byte arrays internally, so mixed encodings can be handled. The IrcClient class can even be used as a component in the Forms Designer. Because it speeds up connect times with some IRC servers, an Ident server is included as well.
php Free Chat is a simple, fast, and customizable chat server that uses the filesystem for message and nickname storage. It uses AJAX to smoothly refresh and display the chat zone and the nickname zone. It supports customized CSS stylesheets and a plugin system that allows you to write your own storage routines.
python-jabberbot is a Jabber bot framework for Python that makes it easy to write simple Jabber bots. One can use these Jabber bots to provide information about running systems, to make Web sites interact with Jabber-enabled visitors, or notify the bot owner about updates or changes that are monitored with custom Python scripts.
libircclient is a small but powerful library that implements the client-server IRC protocol. It is designed to be small, fast, portable, and compatible with RFC standards and most IRC clients. It includes multi-threading support, sync and async interfaces, CTCP and DCC support, and color support. Good documentation and examples are available.
antioch is a Web application for building scalable, interactive virtual worlds. Begun as a MOO-like system for building virtual worlds, the goal was to take the LambdaMOO approach to creating online worlds, and update it in hopes of attracting new players to an old idea. Like many MOO clones before it, antioch uses Python as its internal scripting language. This provides a powerful environment for game authors, while a flexible object model allows for creation of complex in-game objects.