Hi Andrew, When I make backups, I do not backup /dev (I do not use any devices that have not been created automatically). I also backup /usr/local (including all subdirs), because I keep some manually installed programmes there and /boot, where I have a customized kernel (the modules are under /lib/modules and should maybe also be included). Also there may be some more dirs to backup under /var (e.g. mysql databases are under /var/lib/mysql, dosemu's hdimage is under /var/lib/dosemu and /var/www contains the system html-pages).
I use tob (which is available as a debian package) for making backups. It is nice script that uses afio for making backups. It may be more convenient than writing your own script. Greetings, Christian van Enckevort