NetPlug is an extensible multi-connections, multi-protocol, network client program, written in pure Tcl/Tk. Includes a complete Irc client plug in that you should love if you like IrcII 'classic' look & feel (plus customizable style/colors scheme, sound,... Now includes full DCC support (with GUI), ircII like aliases and improved scripting (Tcl!), keywords (your nick...) highlighting, and more
Gale is an open-source messaging system. It provides private messaging and public chat, uses strong end-to-end cryptography for security, and supports a distributed server network with a range of clients (both console and GUI) available. Gale is currently in early alpha testing. See the homepage for the details of its current status.
EPIC4 is a new direction in ircII development. It was originally built upon the ircII-2.6 client and has maintained faithfulness to remain current up to the 2.8.2 release. EPIC is somewhat larger than the stock client (24%), but that is mostly because of the multitude of new features, the dual ANSI/K&R compliant function headers, and the large amount of re-written code in an attempt to make ircii faster, more efficient, and more powerful.
BitchX is the premiere IRC (Internet Relay Chat) client. It originally was a modified version of the popular ircII client, and the features were eventually merged into the EPIC IRC client. The current development is aimed at merging the client back to a current branch of EPIC and bringing compatibility and stability back to the client, while bringing the features that are BitchX into a new client.