IRC client
program which connects to the namesake protocol for communications
Quiet Internet Pager
third-party closed-source freeware multiprotocol IM client
Empathy
open source instant messaging and VoIP client
Miranda IM
Free instant messenger for Microsoft Windows
Colloquy
IRC client
Vision
IRC client
Fire
instant messaging client
Pidgin
graphical multi-protocol instant messaging client
Microsoft Comic Chat
graphic IRC client by Microsoft
Homer
Classic Mac OS IRC client
Finch
command line instant messenger
naim (software)
messaging and chat program
Morpheus
peer-to-peer file sharing client
ii
minimal IRC client
Nettalk
IRC Client for Windows