Skype

Skype (http://www.skype.com) provides an easy to install/use Voice over IP solution. Sadly, sadly, it is not Open Source and not likely to be opened any time soon.

At least with Knoppix 3.9, one can easily download the .deb package from the above mentioned web site and install it with

  dpkg -i skype_...deb

This change is not persistent to my experience. I hence suggest to put the .deb to the home page and to reinstall it whenever one feels like it.