free, distributed and user-friendly IRC / Twitter / XMPP / Campfire / JabbR client for Linux, Windows and Mac OS X based on GNOME / GTK+

Raspberry Pi users running Raspbian can install Smuxi from this release PPA, just run the following commands:

sudo -s bash -c 'echo "deb http://ppa.launchpad.net/meebey/ppa/ubuntu precise main" >> /etc/apt/sources.list'
gpg --keyserver keyserver.ubuntu.com --recv-keys FC6D77D5
gpg --export --armor FC6D77D5 | sudo apt-key add -
sudo apt-get update
sudo apt-get install smuxi-engine

Now you can start the smuxi-server from a shell, for more details see the server how to.