Examples to do:

web servers: apache, nginx, Netty.io (Java), yaws (Erlang)
ldap server
system level files, i.e. nsswitch.con
dhcp server main and auxilary configs for networks
dns server, and their zones (separately)
routing server (i.e. quagga and BIRD)
squid proxy server
iptable, nftables rules.
ssh server
ssh client config (with multiple per-hosts sub-configs)
data bases: mysql, postgresql, couchbase, memcached, Redis
load balancers: NGINX Plus, HAProxy
ipsec / racoon
openvpn server