I just installed Hamachi on my desktop the other day. It's a free, cross-platform VPN application that requires almost no advanced configuration. The UI is simple and straightforward (and pretty nice-looking, actually), and it all just works.

So you're asking yourself - what would I do with something like this? Imagine connecting a set of machines together that are located on opposite ends of the continent (or the world, for that matter) and having them behave like they're on the same local area network. That's the basic premise behind a virtual private network, and Hamachi makes the process of doing this incredibly simple. Once it's set up, you can access network shares and printers, and map network drives on any machine connected to the private network, just like you would be able to if they were on the same LAN. You can even set up private LAN games without having to connect to a centralized server. The Hamachi UI also includes a basic instant messaging client so that you can send messages to other machines on the private network. And all communication over the channel is fully encrypted.

The app is available for Windows (works with XP x64), Linux and Mac OS X, although the OS X version is currently only command-line based. Check it out. My brother and I are planning to play a LAN game of NFS:MW using this sometime next week. Will let you know how that goes. :)