CenterIM is a text mode menu- and window-driven IM interface. ICQ, Yahoo!, AIM TOC, IRC, MSN, Gadu-Gadu and Jabber protocols are currently supported. It allows you to send, receive, and forward messages, URLs, SMSes and, contacts, mass message send, search for users (including extended "whitepages search"), view users' details, maintain your contact list directly from the program (including non-icq contacts), view the messages history, register a new UIN and update your details, be informed on receiving email messages, automatically set away after the defined period of inactivity (on any console), and have your own ignore, visible and invisible lists. It can also associate events with sounds, has support for Hebrew and Arabic languages and allows to arrange contacts into groups. There is also an internal RSS reader and even a LiveJournal client!
CenterIM is known to build and work well under Linux, FreeBSD, OpenBSD, NetBSD, Sun Solaris, MacOS X/Darwin and Microsoft Windows (built with cygwin).