Konversation - Konversation is an IRC client which gives you speedy access to Freenode network's channels...
mIRC - mIRC: Internet Relay Chat client
Kiwi IRC - A hand-crafted IRC client that you can enjoy. Designed to be used easily and freely.
HexChat - HexChat is a fork of XChat with bug fixes and new features.
irssi - Irssi is a terminal based IRC client for UNIX systems.
WeeChat - WeeChat is a fast, light and extensible chat client.