FolderShare is a free application/service that allows you to share your files from across two or more computers at different locations (such as home and work). The way this service works, it that it setups a private peer-2-peer network between to or more computers, and then synchronizes the files between all the computers in the network.
FolderShare consists of two components, 'My FolderShare' and 'FolderShare Satellite'. My FolderShare allows you to manage the file sharing between the two computers. FolderShare Satellite is the software that you run on your computer that allows you to synchronize and share files.
FolderShare Satellite runs in the background on your computer when you're online. Then as you update your files they will be automatically sync with the other devices.
From here you can download FolderShare for Windows or the Macintosh.