A cross-platform (using GNOME/GTK+) IRC client software for advanced users with multiple server support.

A full-featured chat server for high-load websites.

A MSN messenger for KDE.

EZ Intranet Messenger is a messenger client for internal communication.

Pidgin, previously known as Gaim, is a multi-protocol instant messaging client for Linux, BSD, MacOS X, and Windows.

A Lite IM/Chat Client for Second Life

A multi-protocol Instant Messaging client

Empathy project is a Gnome IM/voice/video client reusing Gossip’s UI and using Nokia’s MissionControl.

A simple and nice looking MSN messenger clone

pidgin privacy please project is a pidgin plugin to stop spammers from annoying you.

A project identically to the environment which is known from 3dchat.org

An improved version of GyachE, a feature-rich client for the Yahoo instant messaging protocol

A dedicated multi-platform and open source client for connecting to StatusNet installations

Instant messenger for LAN

IRC utility robot framework for Python

KWallet Plugin for Pidgin IM

IM + Videochat + Free Calls + Cheap VoIP Calling + Social Networks

Twisted is an event-based networking framework for Internet applications.

An IRC to other chat networks gateway

Konversation is a user friendly Internet Relay Chat client.

TUI Twitter Client

Browser XMPP MUC client

rbot is a ruby IRC bot.

Secure Instant Messaging for Companies

Twitter, Wassr, identi.ca, jisko and friendfeed plugin for Pidgin

VooDoo cIRCle is an IRC (ro)bot, scriptable, SSL support, FileSystem, BotNet, advanced security rights for each user.

Twitter viewer

Xfire gaming network access with Kopete

Mithril IRC Services