Generate the list of installed packages. Exclude those packages that have been removed
dpkg --get-selections | grep -v deinstall > installed-packages.txt
acpi-support install
acpid install
adduser install
adium-theme-ubuntu install
aisleriot install
akonadi-server install
alacarte install
alsa-base install
alsa-utils install
anacron install
...
Use this list on another system to set what to install
sudo dpkg --set-selections < installed-packages.txt
Perform the installation. Type ‘I‘ and allow dselect to install of the the packages listed in your list. When it’s finished, type ‘Q‘ and hit the ENTER key to exit dselect.
sudo dselect
If you just want a clean list of installed packages
dpkg --get-selections | grep -v deinstall | cut -f 1 > installed-packages.txt
acpi-support
acpid
adduser
adium-theme-ubuntu
aisleriot
akonadi-server
alacarte
alsa-base
alsa-utils
anacron
...