Snerkel, one of our most helpful members, has a website on networking (wired and wireless), routers, VPN, web servers and much more. It can be found here:
http://www.rce24.co.uk/tech24
Over the months (and years), his website has proved an invaluable resource, for members of this forum in particular.
Popular topics include:
NAT-NAT configurations: Connecting two routers (or a router and firewall) together
http://www.rce24.co.uk/tech24/natnat.htm
VPN
http://www.rce24.co.uk/tech24/vpn.htm
Wireless networking and security
http://www.rce24.co.uk/tech24/air5.htm
File-sharing across a local network
http://www.rce24.co.uk/tech24/rounet.htm