I have been looking into free or open source VPN products, for home / work use.  I have come to the conclusion that Hamachi, and OpenVPN are my favorite picks.

Hamachi is the zero configuration setup, but does depend on a main server to control user passwords and accounts for your connections. There are limitations in the free version but usually works in any situation for home use.

OpenVPN is one that you have to configure, but you can do multiple different setups. You can setup a direct line, or a multi client network with there own keys, or a shared key connection.

I highly recommend the GUI version of OpenVPN this has helped a ton when I was doing the initial configuration.  Here is a great link to setup OpenVPN, very simple to follow.