Windows only: Free application Gbridge sets up a virtual private network between any computer over the internet using your Google account as a starting point. Once set up, Gbridge allows you to share files, connect to and remotely control a computer using VNC, sync folders, and back up files to another computer. If you've got Google Talk/Gmail chat friends using Gbridge, the app provides the same functionality between your computer and theirs. It all sounds a little convoluted, but in effect it's actually a relatively painless way for anyone to setup up a VPN between computers, and assuming you've already got a Google account, it doesn't require you to sign up for anything else. The application could be a bit more intuitive in practice, but in terms of what it accomplishes, it's a winner. Gbridge is freeware, Windows only. Despite the name, it's not associated with Google.