Textual is the world's most popular application for interacting with Internet Relay Chat (IRC) chatrooms on OS X.
Lime chat is a basic IRC client for Mac
Linkinus 2 is a commercial IRC client meant to be for a "rich social experience."
Irssi is a terminal based IRC client for UNIX systems. It also supports SILC and ICB protocols via plugins. Irssi is also available on OS X via homebrew.
Adium is a free and open source instant messaging application for Mac OS X, written using Mac OS X's Cocoa API, released under the GNU GPL and developed by the Adium team. B...