Files to backup before reinstalling ubuntu

Important-files-to-backup

In ~/
.bashrc
.bash_history
In gnome
 with more plugins, .local/share/gnome-shell
 app preferences(terminal key bindings, etc), .gconf

.viminfo 
.vim_rc
.mozilla
.ssh

In /etc
apache2/sites-available (If apache configuration changed)
cron.* (If cron job is running)
default/  (if you have changed deafult params. Take whatever you've changed)
dhcp/dhcpd.conf  (if you have dhcp server setup and conf is changed)
hostapd/* (if installed and configured)
network/interfaces (if changed)
NetworkManager/system-connections/  (for network connections. If changed take other files too.)
environment
hosts
sysctl.conf
rc.conf (for boot up scripts)