> > What is good/bad to backup (tar+gz) on a Debian-system (etc|var|usr...)? >
you want a copy of /etc and /home for sure. /usr/local if you use it, same with /opt. /var is probably ignoarable, unless you need logs. dpkg --get-selections > mypackages, will write all of the packages you have installed on your system to a file. Once you reinstall, dpkg --set-selections < mypackages will restore them.
