lightIRC - lightIRC is a fast, free, Flash-based IRC Client. It supports webcams with an extension!
irssi - Irssi is a terminal based IRC client for UNIX systems.
LiveAgent - LiveAgent is a fully-featured web-based live chat and help desk software. It harnesses the power of a universal inbox, real-time live chat, built-in call center, and a robust customer service portal. Start your free 1 month trial today!
LimeChat - LimeChat is an IRC client for Windows, Mac OS X and iOS. Features
uhChat - uhChat is a chat window software that can be integrated into any website.
WeeChat - WeeChat is a fast, light and extensible chat client.