BitlBee brings IM (instant messaging) to IRC clients. It's a great solution for people who have an IRC client running all the time and don't want to run an additional MSN/AIM/whatever client. BitlBee currently supports the following IM networks/protocols:
We are building an Open Source Jabber/XMPP solution. Our goal is to provide a complete environment for basic instant messaging use, stable and easy to extend for all variants of instant communication use cases.
Spark is an Open Source, cross-platform IM client optimized for businesses and organizations. It features built-in support for group chat, telephony integration, and strong security. It also offers a great end-user experience with features like in-line spell checking, group chat room bookmarks, and tabbed conversations.
Combined with the Openfire server, Spark is the easiest and best alternative to using un-secure public IM networks.