Ayttm is an instant messenger program, supporting various protocols such as MSN, Yahoo, AIM, Jabber, and more. It is the heir of the Everybuddy project, and aims to continue improving the program and addressing its shortcomings.
It is an instant messaging client. Crony IM has support for some commonly used instant messaging protocols, allowing the user to log into various different services from one application. like LAN, GTalk, Yahoo, Facebook.
PhoenixIM, Phoenix Instant Messenger, is an open-source instant messenger project. It features server and client software and a PHP package for online account managing. PhoenixIM needs MySQL and it is recommended to have a server with PHP.
Fire is a multi-protocol instant messenger client for Mac OS X based on freely available libraries for each service. Currently Fire handles AOL Instant Messenger®, ICQ®, MSN® Messenger, Jabber, limited IRC, Yahoo!®, and Apple Bonjour communications.
An open-sourced all-in-one messenging client. The client includes AOL OSCAR, IRC, MSN Messenger, Yahoo! Messenger, and ICQ (OSCAR). Written in Java for cross-platform support.
Internet Relay Jabber (or IRJ) is a Jabber client for IRC. It's useful if you like IRC, but your friends use another IM service. It is written in Perl and uses Net::Jabber and Net::IRC. (This project is no longer under active development)