Finch is a console-based IM program that lets you sign on to AIM, Jabber, MSN, Yahoo!, and other IM networks. It runs on Unixes. It uses GLib and ncurses.
WeeChat is a fast, light and extensible IRC chat client. It runs on many platforms like Linux, Unix, BSD, GNU Hurd, Mac OS X and Windows (Bash/Ubuntu and Cygwin).
Alpine is a fast, easy to use email client that is suitable for both the inexperienced email user as well as for the most demanding of power users. Alpine is based on the Pine® Message System, which was also developed at the University of Washington. Alpine can be learned by exploration and the use of context-sensitive help. The user experience is highly customizable through the use of the Alpine Setup command.