Hamachi is genius. Install a simple client on Windows or Mac and you have a VPN that is transparent.
As an example, I can now browse my Mac mini hard drive at work through a normal explorer window. Other uses? Well why not do VNC over the Hamachi network instead of over the internet. That means that I don’t have to open my VNC ports on the my router, reducing risk.
It appears to be secure, but is definitely for confident geeks, not man in the street.
I started investigating all this here.
[NB the post used to have Hamchi as the title. Random misspelling meant I got some traffic. Now corrected]