BitchX
A heavily modified ircII client, which includes many features such as built-in CDCC (XDCC), flood protection, port scanning, advanced TCL, a CD player, a mail client, screening process, etc.

XChat
A graphical IRC Client (Internet Relay Chat) based on GTK.

epic
The (E)nhanced (P)rogrammable (I)RC-II (C)lient

ircII
An IRC client that runs under most UNIX platforms.