A few weeks back I recommended Cubby, a service which allowed you to keep files in sync purely through LAN. The only downside was that it was a paid service. (I wish I hadn't paid for it now)
BitTorrent has just released a free tool which allows you to share unlimited files between machines completely free. By unlimited, I mean the amount of storage your machines actually have.
So if you're like me and use two Mac's regularly, an iMac at home and a Macbook Air on the go - you'll want to keep your files in sync between the two machines. You simple download the BitTorrent Sync app on whichever machines you want to sync, pair them up, choose a folder and start putting files in it to start syncing.
They make it clear that your files are never stored in the cloud and are encrypted so your files will always be secure and private.
There are a bunch of other useful features too.
One-way synchronisation allows you to sync files from one machine to another without the other being able to add files or delete files from your original computer.
One-time secret allows you to sync files for 24 hours. So if you want to sync files for a limited time only you can use this.
Files can sync via LAN or over the cloud, providing both machines are connected to the internet. It's a brilliant and free way to keep files in sync between various machines which I'll be using from now on.