Colloquy is an IRC (Internet Relay Chat) and SILC (Secure Internet Live Conferencing) client for Mac OS X. Striking is the surface, which in contrast to other IRC clients is harmoniously integrated into the Mac OS X environment.
This IRC client is very open for expansion. It offers for example AppleScript support and can be extended with plugins to missing functions. The appearance of the chat window can be customized with Styles. File transfers also include functions of Colloquy.