What about my list of packages?

Create /usr/local/bin/dump_dpkg.sh and chmod it 755:

#!/bin/sh /usr/bin/dpkg --get-selections > /etc/dpkg.packagelist.txt

Create a cron job to run it automatically every night:

you@box:~$ sudo crontab -e 0 23 * * * /usr/local/bin/dump_dpkg.sh

Now you'll have a file /etc/dpkg.packagelist.txt, updated once daily, to restore your installed applications with. Restore that file, then feed it to dpkg, and you're set!

you@box:~$ sudo dpkg --set-selections < /tmp/etc/dpkg.packagelist.txt