Coccinella is a free and open-source cross-platform chat client with a built-in WhiteBoard for improved collaboration with other people. Other key features of Coccinella include:
File Transfer
Plugin system
Group chat (MUC)
Avatars and Emoticons
Multi-lingual and internationalized
Secured connections (TLS and SASL)
Open standard instant messaging protocol (*)
Coccinella can Connect to any Jabber/XMPP instant messaging server. You can either use a public server, or you can deploy your own server. In the latter case, you can opt to federate your server with the public Jabber/XMPP network.