LogMeIn - Hamachi

Wanna play with your friends across the globe via LAN on WAN. It's now possible with the use of a special free application called "LogMeIn Hamachi". LogMeIn Hamachi is a VPN service that easily sets up in 10 minutes, & enables secure remote access to your network, anywhere there's an Internet connection. It works with your existing firewall, and requires no additional configuration. Hamachi is the first networking application to deliver an unprecedented level of direct peer-to-peer connectivity. It is simple, secure, and cost-effective.

You can download the application at (https://secure.logmein.com/products/hamachi/vpn.asp?lang=en).