command memo:
echo deb http://packages.medibuntu.org/ karmic free non-free | sudo tee -a /etc/apt/sources.list
wget -q http://packages.medibuntu.org/medibuntu-key.gpg -O- | sudo apt-key add -sudo apt-get update
sudo apt-get install skype
I also see a another method (better)
sudo wget http://www.medibuntu.org/sources.list.d/karmic.list-O /etc/apt/sources.list.d/medibuntu.list
sudo apt-get update&& sudo apt-get install medibuntu-keyring && sudoapt-get update ...
//PPA的源
deb http://ppa.launchpad.net/chromium-daily/ppa/ubuntu karmic main
deb-src http://ppa.launchpad.net/chromium-daily/ppa/ubuntu karmic main