https://help.ubuntu.com/community/Medibuntu
This command should be run in the Terminal (Applications → Accessories → Terminal):
sudo wget --output-document=/etc/apt/sources.list.d/medibuntu.list http://www.medibuntu.org/sources.list.d/$(lsb_release -cs).list && sudo apt-get --quiet update && sudo apt-get --yes --quiet --allow-unauthenticated install medibuntu-keyring && sudo apt-get --quiet update
Medibuntu's repository is deactivated by upgrading to a newer Ubuntu release, so you should run this command again after the release upgrade.
You may also wish to add the following packages. The first will cause many apps from the Medibuntu repository to appear in Ubuntu Software Center (Ubuntu 9.10+) or Add/Remove Applications (versions prior to 9.10). The second will allow users to generate crash reports against Medibuntu packages and submit them to the Medibuntu bugtracker.
sudo apt-get --yes install app-install-data-medibuntu apport-hooks-medibuntu
