Some people do not have a permanent access to the Internet or the connection is limited; as an example, a friend can't download files larger than 10 mb. So how to install applications offline, in Ubuntu? Obviously, the packages have to be downloaded from another computer but this should include all the dependencies or else it would be useless.
APTonCD is an application that backs up all of your packages downloaded from apt-get or aptitude onto a CD or a DVD. This is perfect if you ever lose an internet connection or if you want to quickly install new operating systems without having to remember a long list of packages you needed to install.