I am trying to copy all of the packages I have installed on one Debian machine to another Debian machine without doing another
apt-get install and downloading all of the package all over again.
You can also create a package proxy, we use approx
Then the real repository servers are specified in the approx.conf, like:
debian http://ftp.debian.org/debian security http://security.debian.org/debian-security volatile http://volatile.debian.org/debian-volatile
In all machines you want to install just place the following to /etc/apt/sources.list:
deb http://<hostname>:9999/debian/ squeeze main contrib non-free deb http://<hostname>:9999/security/ squeeze/updates main contrib non-free etc.
When first machine is downloading the packages, they go from the internet and are stored in the cache of approx. All other machines download the packages from the cache directly.