If you've ever wanted a security-focused, Dropbox-like file and folder syncing option, BitTorrent decided to answer your wishes with BitTorrent Sync. Previously in private alpha, BitTorrent Sync is now available to the public for Windows, Mac and Linux.
Although BitTorrent Sync syncs your folders and files much like you'd expect from a service like Dropbox, you set it up a little differently. When you start for the first time, you choose where you want a folder to be and then BitTorrent Sync gives you a secret. When you install BitTorrent Sync on another computer, you can provide that secret and link the folders together. They'll synchronise with each other securely, peer-to peer. That means nothing goes to the cloud, but rather each computer syncs data with the other directly.
If you want to sync a different folder, regardless of its location, you can just add it to BitTorrent Sync and it'll work just like the folder you set up initially. The service is very easy to use, despite its security focus (which often involves sacrificing convenience), and doesn't cost you anything to use. If you're looking for a simple way to sync any folder and its contents on your computer for free — whether you care about security or not — give BitTorrent Sync a try.
BitTorrent Sync [BitTorrent Labs]